Webtoons Secret Class Spoiler Synopsis & How to Read for Free

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The webtoons series Secret Class spoiler features a thrilling story about secretly interacting with one’s step-sister and step-mother under one roof. Many might recognize it from advertisements. This work is appealing not only because it features many beautiful women, but also because its artwork and situations are realistic. This article will thoroughly explain everything from spoiler plot summaries and highlights to reviews of the manga ‘Secret Class,’ as well as how to read it for free without using illegal sites. As a result of actually using and investigating multiple manga services, it was found that there are no apps or services where you can read the entire series for free.

Webtoons Secret Class Spoiler Synopsis & How to Read for Free

Secret Class Spoiler Synopsis & How to Read for Free

Secret Class Manga Details and Synopsis

Genre: Seinen Manga / Adult Manga
Volumes: 74 volumes (as of May 2025)
Authors: Mina-chan, Oh Gang-cheol
Publisher: Rush! Editorial Department

Dae-ho was adopted by the Yuuki family after losing both his parents in a traffic accident when he was 12 years old. Dae-ho spent seven years with his new family in the Yuuki household and grew into a young man. However, his knowledge of sex remained at an elementary school level.

One night, he witnessed his foster parents engaging in sexual activity and became aware of his own sexual arousal for the first time. However, not knowing how to express his sexual desires, Dae-ho spent his days in distress and frustration. Noticing Dae-ho’s feelings, his foster mother, Eun-ae, decided to take it upon herself to provide him with sex education, thinking, “I… have to teach him…” The ‘Secret Class’ that began after the family had gone to sleep involved not only his foster mother but also his step-sisters…


Secret Class Spoiler Synopsis (Chapters 1-4)

Webtoons Secret Class Spoiler Synopsis & How to Read for Free

The protagonist, Dae Ho, becomes an orphan at age 12 after a car accident with his parents. He’s taken in by his father’s friend, the Yoo family, and lives a happy, seemingly normal life with his new father, mother, and two older sisters.

One night, Dae Ho accidentally witnesses his adoptive parents, Jung and Mari, having sex. Due to his limited sexual knowledge, Dae Ho doesn’t understand what they’re doing. The next morning, he has a wet dream, which Mari discovers while doing laundry. Mari becomes concerned that Dae Ho might not know how to masturbate. That night, she visits his room and asks him, “Do you want to try masturbating?”

While Jung is away on a business trip, Dae Ho begins to learn about sex, including ejaculation, using Mari’s body. When Jung returns from his trip, Dae Ho then asks his older stepsister, Mi-Ah, to help him masturbate. Dae Ho’s actions escalate, eventually leading to the two of them having sex.

Thus, Dae Ho’s secret lessons about sex begin.


Secret Class Spoiler Synopsis (Chapters 5-8)

Webtoons Secret Class Spoiler Synopsis & How to Read for Free

In Volume 4, Dae Ho becomes intimate with his stepsister, Mi-Ah. From then on, he continues his relationship with Mi-Ah while also maintaining his relationship with Mari.

Unbeknownst to them, Dae Ho and his family members have fallen into a sexual love triangle within their own home. They indulge in their desires, carrying a bomb that could instantly shatter the family if exposed, yet their urges know no bounds. Dae Ho eventually accepts an invitation from Sua, a pure and beautiful girl with black hair, finally initiating a relationship with a woman outside the family.

Does the fact that “intimacy with a woman outside the family” seems like a “fresh experience” indicate that even the author is influenced by this work?


Secret Class Spoiler Synopsis (Chapters 9-12)

Webtoons Secret Class Spoiler Synopsis & How to Read for Free

Dae Ho has finally had a relationship with a woman outside the family. Mi-Ah senses this change in Dae Ho and tries to trip him up by asking, “Did you do it with another woman besides me?” Despite his impure actions, pure-hearted Dae Ho can’t lie and inadvertently reveals that he has been intimate with other women.

Although shocked by his words, Mi-Ah starts their “lesson” as usual, but a possessive feeling towards Dae Ho has begun to grow within her. She now swings between joy and sorrow based on the words Dae Ho gives her during their intimate acts. Mi-Ah firmly resolves once again that she “has no intention of letting Dae Ho go to other women.” It seems this family’s sense of morality has been thrown out with the trash on burning garbage day.


Secret Class Spoiler Synopsis (Chapters 13-16)

The chapters begin with Dae Ho having outdoor sex with Sua in a forest. Due to an unforeseen accident, Dae Ho finally engages in intercourse with his adoptive mother, Mari. The author notes that even they are no longer surprised by outdoor sex, expressing more surprise that Dae Ho and his adoptive mother hadn’t reached full intercourse until now.

Mari can’t hide her confusion as Dae Ho, despite this being his first time with her, proceeds with strangely experienced movements. During their intimacy, Mari realizes that Dae Ho is seeking the warmth of a parent. While it seems she may have already lost something crucial as a parent, perhaps it’s still fitting to call her a mother for noticing this.


Secret Class Spoiler Synopsis (Chapters 17-20)

These chapters kick off with Dae Ho and Mi-Ah having outdoor sex on the beach. This leads to a turbulent chapter where a homeless man suddenly appears and discusses the behind-the-scenes production of this very work.

Some readers might find this confusing, but it’s exactly as it sounds. The homeless man reveals insights into manga production, which, of course, the characters in the manga don’t understand, leading to an atmosphere of bewilderment as the author’s confession unfolds. If you’re curious about these behind-the-scenes details, you’ll have to read the manga yourself.

These chapters also depict Dae Ho’s sexual urges finally exploding after his first few days of abstinence since becoming intimate with women. This is the only place where you can see Dae Ho beginning to develop a sadistic side.


Secret Class Spoiler Synopsis (Chapters 21-24)

While sleeping next to Mi-Ah’s best friend, Juri, Dae Ho accidentally touches Juri’s private parts and reaches climax. Juri, awakened by the splashing liquid, takes Dae Ho to the bathroom. Declaring she’ll “teach him about women,” Dae Ho begins an extracurricular lesson with his stepsister’s best friend.

Juri, a woman who initiates sex with her best friend’s stepbrother in someone else’s bathroom, is likely the most outrageous character in the series. Has the concept of chastity completely vanished from this world? Hajin, the only family member not yet involved with Dae Ho, witnesses their suspicious relationship. Hajin despises herself for even wondering, “Did he do it with Juri?”


Secret Class Spoiler Synopsis (Chapters 25-28)

Hajin spends the night with Dae Ho in a sleeping bag. Hajin, who was the only seemingly normal person in this series, also falls prey to Dae Ho’s schemes. Unable to move properly in the cramped space, Hajin becomes agitated as Dae Ho presses something hard against her. And with her stepbrother’s “member,” Hajin loses her virginity.

She then questions Dae Ho about his suspicious relationship with Juri, which she had doubted earlier. However, Dae Ho, despite his utterly broken sense of morality, gives a serious reply, saying it’s a “matter of privacy.” Enraged by Dae Ho’s response, Hajin retaliates by punching him. Almost all the family members in the Yoo household have now become intimate with Dae Ho. At this point, only the stepfather remains.


Secret Class Spoiler Synopsis (Chapters 29-32)

Intimate acts with Mi-Ah and Mari are depicted again after a long time. There’s a surprising level of “growth” from Chapter 1, with an overnight tryst with Mi-Ah and outdoor sex with Mari in the aunt’s garden. However, at this point, such events are commonplace, and one can only admire the refreshing casualness, as if to say, “It’s naive to question any of this.”

After their encounter, Dae Ho and Mari head to the bathroom. In this relaxing space, Mari confronts the question she’s had while continuing her relationship with her stepson: “What kind of person am I?” You might wonder, “Why now? Why not earlier?” But in the face of this work, perhaps all such questions are meaningless.

Secret Class Spoiler Synopsis (Chapters 33-36)

Dae Ho and Mari were in the middle of an intimate act in the bathroom. Dae Ho, whose excitement wouldn’t subside after one round, was about to go for a second. Mari declined, opting instead to clean her aunt’s house, then began preparing dinner. Even before dinner, Mari succumbed to Dae Ho’s lewd gaze, and the two once again engaged in sexual activity. As Mari continued to be intimate with Dae Ho, her body became increasingly wanton. Dae Ho and Mari, seeking each other out, had transformed from parent and child into a man and woman.

While they were engaging in acts during the aunt’s absence, the aunt returned home earlier than expected and witnessed them. Instead of condemning them, the aunt, after hearing their story, expressed support for Mari to live freely.


Secret Class Spoiler Synopsis (Chapters 37-40)

Upon returning home from his aunt’s house, Dae Ho heard from Mi-Ah that they would be having a drinking party tomorrow, inviting Juri. The three of them—Dae Ho, Mi-Ah, and Juri—enjoyed the party, but eventually fell asleep. Dae Ho, who woke up first, touched the sleeping Juri.

Soon after, Juri also woke up, and Dae Ho and Juri reached climax. Mi-Ah, noticing their actions, questioned Dae Ho about his relationship with Juri while Juri was taking a shower. Dae Ho honestly confessed that he and Juri had become intimate. Mi-Ah then began to seduce Dae Ho to cool down her flushed body, and Juri, returning to the room, witnessed Dae Ho and Mi-Ah in the act. They then proceeded to engage in a threesome.


Secret Class Spoiler Synopsis (Chapters 41-44)

The Yoo household became lively when Dae Ho’s friend, Yang, and Yang’s sister, Sua, came to visit. As the five of them, including Mi-Ah and Juri, enjoyed playing games, Sua asked Dae Ho to show her the white birch trees in the backyard.

Dae Ho and Sua went to the backyard and engaged in sexual activity there. Juri secretly peeked in on their act, but afterward, nothing particularly eventful happened, and Juri and the others returned home in the evening. That night, Dae Ho, still filled with excitement, had sex with Mari.

The next day, Dae Ho accidentally witnessed Hajin feeling aroused, which led him to engage in an act to help Hajin release her sexual tension. Meanwhile, Jung, who was on a business trip, was enjoying a night with women at an erotic club with his friends.

Here’s the English translation of the provided text, with all character names replaced by their Korean equivalents:


Secret Class Spoiler Synopsis (Chapters 45-48)

Dae Ho visits Hajin’s room and forcefully initiates an intimate act. Although Hajin initially resists, her body honestly responds, and she embraces Dae Ho repeatedly. After their lovemaking, Dae Ho receives an invitation from Mari. However, having just embraced Hajin multiple times, his lower body doesn’t respond. The next day, Mari secretly prepares revitalizing dishes, and Dae Ho regains his libido and goes to Mi-Ah for a night visit.

The following day, the Mi-Raeng couple (Mari’s husband, Jung’s, friends) come to stay overnight at the Yoo family home. That night, Mi-Raeng’s wife, Ri-Ae, accidentally witnesses Dae Ho and Mi-Ah indulging in sexual activity. After witnessing their tryst, Ri-Ae begins to become aware of Dae Ho. Invited to the beach by Dae Ho, Ri-Ae appears in a bikini. There, she receives an oil massage from Dae Ho…


Secret Class Spoiler Synopsis (Chapters 49-50)

Dae Ho and Ri-Ae move to a deserted beach and begin the oil massage. Dae Ho’s hand eventually moves to Ri-Ae’s lower abdomen, toying with her body. When Ri-Ae protests, Dae Ho exposes his impressive “member.” Ri-Ae is shocked by its unprecedented size. Noticing her agitation, Dae Ho forcefully makes her perform oral sex, then penetrates her from behind. Despite resisting Dae Ho, Ri-Ae’s body drowns in pleasure, accepting everything.

Upon returning home, a dinner party is held, and Ri-Ae reflects on her act with Dae Ho. When Ri-Ae leaves the table mid-meal, Dae Ho follows her and orders her to come to his room late at night. Threatened by what happened earlier, Ri-Ae is compelled to go to Dae Ho’s room late at night… Ri-Ae, the new heroine, falls into Dae Ho’s hands. It’s thrilling to see Ri-Ae, who once looked down on Dae Ho and was so haughty, gradually becoming submissive!


Secret Class Spoiler Synopsis (Chapters 51-55)

Dae Ho invites Ri-Ae into his room and pushes her onto the bed. As he gives pleasure to her, she initially resists with words but gradually begins to moan. Dae Ho roughly thrusts his hips against Ri-Ae, who is unsatisfied with sex with her husband.

As a result, Ri-Ae instantly succumbs to pleasure. The act doesn’t end after one round; they continue to be intimate until morning. Furthermore, Dae Ho seizes the opportunity to have sex while the family is eating breakfast. Dae Ho successfully turns Ri-Ae into his sexual slave. He makes her promise to come to the house regularly and sees her off as she returns home. In the quiet house, Mi-Ah and Mari are absent, leaving only Dae Ho and Hajin.

In fact, Hajin had been peeking in on Dae Ho and Ri-Ae’s act and had been aroused since last night. She then utters seductive lines to Dae Ho, demanding his body. Moreover, within her heart, she begins to awaken to a love distinct from family affection. Just then, Mari, Mi-Ah, Juri, and Juri’s dad arrive…


Secret Class Spoiler Synopsis (Chapters 56-57)

Dae Ho narrowly avoids being caught with Hajin. That night, he has a good time at a drinking party with Mi-Ah and Juri. Afterward, Mi-Ah falls asleep from drinking, signaling the end of the gathering. Dae Ho returns to his room and gets into bed, but Juri pays him a night visit. Unable to resist her service, Dae Ho enjoys ample pleasure before the roles are reversed. As he slowly stimulates Juri’s entire body, Mi-Ah suddenly enters the room.

Mi-Ah is angry at Juri for monopolizing Dae Ho and demands that she leave immediately. She then ignores Juri and becomes intimate with Dae Ho. However, Juri, unable to hold back, joins the two, and they engage in a threesome. Meanwhile, Hajin is peeking in on their act from outside the room…

Here’s the English translation of the provided text, using the Korean character names where appropriate:


We will post the latest chapters of the webtoon ‘Secret Class’ here

Secret Class Characters

  • Dae Ho The protagonist of this work. He lost his parents in an accident when he was 12 and was taken in by his father’s friend’s family, the Yoo family. One day, he witnesses Mr. and Mrs. Yoo intimately engaging, which awakens his sexuality. Being an inherently pure boy, he has very little sexual knowledge.

  • Yoo Mari The beautiful woman depicted on the cover. She is the wife of Yoo Jung, who adopted Dae Ho, and is always smiling and kind, acting as the sun that brightens the Yoo household. She worries about Dae Ho’s ignorance regarding sex and resolves that she must be the one to teach him. She’s a mother with such a nice body that even her daughter acknowledges it.

  • Yoo Mi-Ah and Hajin Mi-Ah is the Yoo family’s eldest daughter, a 22-year-old university student. She has a seemingly intimidating appearance but is a very kind and dependable older sister. The second daughter, Hajin, is quite an indoor person and spends a lot of time in her room, with little conversation, making Dae Ho feel that she keeps a certain distance from him.


Highlights of “Secret Class” Manga

Full-Color Pages and Realistic Erotic Scenes!

“Secret Class” is available in full color on Comic Seymour. This allows you to enjoy more realistic bedroom scenes than in black-and-white manga. The characters’ skin is depicted vividly, so you can truly appreciate the difference from other manga. Furthermore, all the female characters in this work are beautiful and sexy. Each one has a unique personality, and their expressions and bodies are drawn in fine detail, so you’re sure to be captivated by them.

Anything-Goes Storyline is Engaging

In “Secret Class,” set in the Yoo household, impossible things happen one after another. It’s a continuous stream of intimate events with the beautiful adoptive mother and sisters, leaving no time to catch your breath. The story in this work truly features an anything-goes development… Things you thought “that might happen!?” are depicted one after another, making it a manga that fulfills fantasies.

Easy-to-Accept Setting and Depiction for Smooth Reading

This work depicts erotic events within a family, but strictly speaking, the characters are not blood relatives. Therefore, it’s a setting that is easy to accept even for those who might feel uncomfortable with “strict incest themes.” However, the relationship is still familial. The appeal lies in the sense of taboo—”this is happening within a family.” You’re sure to empathize with the psychological depiction of characters unable to resist their desires, even though they know it’s wrong. The situations alone make this a thrilling work.

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