There are a total of 13 endings in I ☆ Can, and 8 of them are bad endings. Before you go through the endings, I suggest you read the following paragraph below in order to have a better understanding about the the main antagonist of the visual novel; Kouji Terada.
Ryouta Tendou was the grandson of Yoshinobu Tendou who was the former president of a major entertainment production company. It turns out that his grandfather expelled Terada from the entertainment industry because he was preying on the idols. During this visual novel, Terada aimed on seeking revenge against his grandfather by making his grandson suffer. This would explain why he aimed to sexually assault the people that are close to Ryouta such as Miyu and Reina.
Miyu - Pure Love Ending
Miyu managed to make a huge hit on her performance as an idol without being too reliant on Qupu's magic thanks to Ryouta's support. Qupu then reminded Ryouta and Miyu that he has no reason to stay anymore since Miyu has finally reached her dream. He bid both of them farewell before going back to Dreamcastle. After Qupu disappeared, Ryouta and Miyu engaged in sexual intercourse as a form of celebration for Miyu's success. Later on, Reina arrives at Ryouta's house and reminds Miyu that since they no longer of the ability to transform, the real competition between them as idols begins. They will have to put in all the effort they have in order to aim for the top. Miyu also stated that she feels confident as long as Ryouta is by her side. Reina told them to do their best before leaving. From then on, Ryouta will continue to support Miyu in the entertainment industry.
Miyu - Transformation Ending
When Miyu managed to reach her dream on becoming an idol and Qupu returned back to Dreamcastle, Miyu had no choice but to immediately retire from the entertainment industry. Since she heavily relied on Qupu's magic, the quality of her performance would falter without her ability to transform. With that being the case, Ryouta and Miyu decided to have sex one more time before the remains of Qupu's magic fades away. From this point, Miyu and Ryouta both intended to keep on living happily together.
Miyu - 3P Ending
When Reina arrived at Ryouta's house after Miyu's success, Reina asked if Ryouta would be able to help her in the entertainment industry. Miyu responded to Reina out of jealousy, stating that Ryouta only belongs to her. This ultimately led both of these girls to compete on who will get assisted by Ryouta in order to become a top idol. This was done in terms of who would give the most sexual pleasure to Ryouta which led to an MFF threesome. The rivalry between Miyu and Reina continues on.
Miyu - Bad Ending Yuuto Edition No. 01
When Ryouta and Miyu started to have sex after Miyu's successful performance, Ryouta was surprised that Miyu wasn't a virgin. She stated that her virginity was already taken by a male idol; Yuuto Yamashita. Miyu explained to Ryouta that since she failed at her previous live performance and had an argument with him, she ran to a nearby park where she met Yuuto and relied on him for support. Yuuto brought Miyu to his apartment and it is revealed that just like Ryouta, Yuuto has feelings for her as well. Because of that, he brought himself to have sex with her. Miyu intially refused but she was unable to resist as she was overwhelmed by the pleasure. They eventually had sex before Miyu returned to Ryouta's house.
Ryouta was enraged on the fact that he sacrificed so much for Miyu's sake and yet she ended up having sex with someone else. Ryouta became violent during the sexual intercourse with Miyu and afterwards, Ryouta no longer wants to work as her manager. Miyu begged him to come back but he refused because he no longer had the confidence to truly love her anymore. He decides to work for other idols at the request of Tomomi. Although he was happy for Miyu's success, he is now aiming to raise an idol that will surpass her in order to accumulate Miyu's regrets on her past actions.
Miyu - Bad Ending Yuuto Edition No. 02
Miyu kept meeting with Yuuto in the park multiple times, which resulted in her to develop feelings for him. Yuuto provided support for her by sharing the difficult times he faced in the entertainment industry and how he overcame them. He also shared his email address with her in case she wants to talk to him again. Eventually, Miyu's feelings for Ryouta had diminished and she's no longer able to transform into an idol whenever they kissed. This can only happen when she kisses Yuuto. Afterwards, Yuuto brings Miyu to his apartment where they had sex.
Miyu stayed in Yuuto's apartment overnight and when it was morning, Ryouta arrived there and desperately wanted Miyu back. At this point, Miyu doesn't want anything to do with Ryouta anymore as she is now in love with Yuuto. Later on, Miyu gets completely captivated by the sexual pleasure that Yuuto gives.
Miyu - Bad Ending Yuuto Edition No. 03
This ending has some extra scenes that root off from the previous one (Yuuto Edition No. 02). A few months after Miyu started to live with Yuuto, she wants to move back to Ryouta's house. Miyu didn't feel at ease to live with Yuuto anymore because of his massive popularity as a male idol. Ryouta reluctantly accepted Miyu back and she was able to transform again after kissing him. However, Ryouta noticed that Miyu's behavior was not the same as before, especially when they had sex. Because of that, Ryouta couldn't really bring himself to truly love Miyu.
Miyu - Bad Ending Terada P Edition
After Miyu failed on her live performance, Terada provided her support by setting up a new program that focuses only on her. However, this was all an act that will give him the opportunity to rape her. When Ryouta attempted to save Miyu, he got restrained by multiple men and was brought to the broadcast stage along with Miyu. After Miyu got gangraped by multiple men, Terada revealed to Miyu that Ryouta got an erection after seeing what she went through. Miyu was upset and felt she has been betrayed by the person she really loved, which ultimately broke her. Terada then convinced Miyu to let everything go and surrender herself to her own desires. When he kissed Miyu in the lips, she transformed into an evil version of herself where she becomes completely addicted to sex.
Terada then brought Ryouta to a love hotel where they forcibly had sex with Miyu. Ryouta eventually passes out after ejaculating multiple times and Terada tells Miyu to kill Ryouta. Miyu complied and Terada tells Negishi to dispose Ryouta's body in order to cover his tracks. From this point onwards, Miyu continuously had sex with multiple men, and Terada uses her to produce pornographic videos for the AV industry.
Miyu - Bad Ending Tooru Edition
Tooru Takasaki kidnapped Miyu and brought her to a love hotel. Tomomi informed Ryouta on what happened to Miyu and they rushed towards where she was located. When they got there, Ryouta was restrained by Tomomi, which revealed that she was a part of Tooru's scheme as well. Apparently, Tooru has the ability to captivate any woman into sexual pleasure, allowing him to manipulate them which is what happened to Tomomi.
When Tooru managed to captivate Miyu into sexual pleasure, along with Reina who also got kidnapped, Terada who was also present in the love hotel ordered Tomomi to kill Ryouta and dispose his body. If she does that, she'll have sex with Tooru again. Tomomi complied and strangled Ryouta, causing him to pass out from asphyxiation.
Miyu - Bad Ending Takashi Edition
Takashi invites Miyu and Ryouta to go on a group date along with other stand up comedians and idols. Miyu accepted the invitation, but Ryouta felt reluctant about this. When they arrived, they started to play what was called "King's Game." Things were initially fine, but later on, more inappropriate actions were done towards Miyu and Ryouta didn't feel comfortable about that. As Ryouta and Miyu left the party, they got into an argument. Afterwards, Ryouta decided to go home by himself while Miyu came back to the party to resume the King's Game. However, she noticed that the idol girls that were in the pub before were missing. Miyu sensed that something was wrong and decides to go home, but Takashi and his acquaintances prevented her from leaving. At this point, Miyu understood what Ryouta was complaining about, but it was too late for her. Miyu ended up getting gangraped, and she eventually got overwhelmed by the sexual pleasure. She was also given a drug that promoted her addiction to sex. Eventually, Miyu abandoned her dreams on becoming an idol and instead allowed herself to get captivated in sexual pleasure.
Miyu - Bad Ending Takuya Edition
When Ryouta got back home from the TV station, he was shocked that Miyu wasn't there. He went to different places where Miyu might be, but he was unable to find her. 2 days later at the TV station, he found a DVD set that were given by an unknown fan of Miyu. When he played it on his TV, he saw that Takuya is the one responsible for the disappearance of Miyu. Takuya became so obsessed with Miyu that he followed her back to Ryouta's house where he then sexually assaults her. He also attempted to make Miyu transform into an idol by kissing her, but it couldn't be done since she doesn't have any feelings of attachment towards Takuya. This made him very angry and upset.
When the DVD finished playing, Ryouta dashes out and goes to Takuya's place in order to save Miyu. However, when he was stopped by a red light at a public intersection, he got stabbed in the back by Takuya. Ryouta collapsed on the floor and passes out from blood loss.
Reina - Happy Ending
Jinzou Negishi who was an aquiantance of Terada, revealed to Ryouta that he secretly took pictures of him living with Reina. Negishi told Ryouta to comply with the orders giving by Terada, otherwise he will leak the photos which can negatively affect the lifestyle of Ryouta and Reina. If Ryouta refuses to comply, Negishi would leave in an angry manner and Ryouta would explain to Reina about the situation they are currently in. Reina was happy that Ryouta didn't comply and she declared to her fans that her next performance as an idol will be her final one before she retires. If she stopped working as an idol, it wouldn't matter for Negishi leaking the photos. Afterwards, Reina aims to become a reliable wife for Ryouta.
Reina - Bad Ending
If Ryouta decided to comply, Negishi will bring him to a room where Terada is present, along with Reina. Ryouta is then forced to watch Reina getting raped by Terada. Afterwards, Terada forces Reina to put a remote controlled vibrator in her vagina and keep it in there during her live performance. During that time, she was unable to hold back her orgasm as the intensity of the vibrator became stronger, causing her vaginal fluids to spill out. This caused the audience to be in distraught and negatively affect Reina's reputation. From then on, Reina was used to satisfy the sexual desires of multiple men and Ryouta couldn't do anything about it.
During a celebration, Tomomi Minamino was completely intoxicated from drinking and told Miyu to go buy more alcohol. While Tomomi and Ryouta were alone together, Tomomi saw Ryouta having a similar resemblance of her husband that died 12 years ago. Because of that, Tomomi started to build up some love and affection towards Ryouta which led to her having sex with him. When Miyu returned from the store, she was devastated to see that Tomomi is having sex with Ryouta, whom she loved. Miyu ran away and Ryouta attempted to follow her, but he was stopped by Tomomi. The sexual pleasure he got from her overwhelmed him, forcing Ryouta to stay with her.
Later on, Miyu's performance as an idol diminished drastically. Seeing that Miyu no longer has the motivation to perform as an idol, Tomomi decided to sell her to an unknown assailant. From this point forward, Ryouta now works for Tomomi and they live happily together.