Nani mo Iwanai
1-2) two childhood friends are secretly in love with each other. One day the dark-haired boy, Emi, begins to date a girl. Jealous, Iori, steals the girl to sabotage them. Later on, it turns out that the girl has liked Iori all along and Emi knew about it. To hinder her, he started to get close to her. 3) MC is an amnesiac high school teacher and returns to his alma mater. He meets a mysterious high schooler, Zen, who MC seems to have forgotten. Turns out Zen is his adopted brother and both were lovers. In the last three years MC has forgotten, MC's father supposedly died in an accident and Zen and MC fell down the stairs after they were caught by MC's mother. Zen has been comatose since then. The last few pages reveal that MC pushed his father down the stairs when he found out that he wanted to send Zen away.
Kowagaranai de, Soba ni Ite