Second-year middle schooler Nao Takanashi loves her older brother Shuusuke to the point where she has developed a brother complex. Wanting her brother to see her as a woman, Nao makes advances toward him on a daily basis, which often results in Shuusuke succumbing to and encouraging more of her teasing. One day, while throwing away porn magazines from her brother's room, Nao finds an album containing his childhood photos—none of which include her. Having discovered the truth behind her family relationships, Nao becomes ever more affectionate toward Shuusuke. However, it does not take long for her dreams of monopolizing her brother to be put in jeopardy.

When 16-year-old Nanako Misonoo enters the prestigious all-girls Seiran Academy, she believes a bright future awaits her. Instead, the unlucky girl finds herself dragged into a web of deceit, misery, and jealousy. On top of that, she is chosen as the newest inductee of the Sorority, an elite group whose members are the envy of the entire school. Having none of the grace, wealth, or talent of the other members, Nanako quickly draws the ire of her jealous classmates—especially the fierce Aya Misaki. To cope with her increasingly difficult school life, Nanako recalls her days through letters to her former teacher, Takehiko Henmi, whom she affectionately calls onii-sama (big brother). She also finds comfort with her four closest friends: her childhood friend Tomoko Arikura, the sociable but erratic Mariko Shinobu, the troubled musician Rei Asaka, and the athletic tomboy Kaoru Orihara. An impassioned drama about the hardships of bullying, Oniisama e... chronicles a young girl's harsh life at her new school, as she endures cruel rumours, heartless classmates, and countless social trials.

A prequel to Cogimyun covering her life at flour school before she runs her grandfather's apartment complex. Episodes air within the Millenia Girl live action program and then get released for a limited time later in the day on Sanrio's official YouTube channel.

Self-professed home security guard Mahiro Oyama has not left his home in years, secluding himself in his room playing erotic visual novels. This depraved lifestyle causes his prodigious sister, Mihari, to worry about his well-being. In hopes of solving this problem, she devises a plan to rehabilitate him back to normalcy. The first part of Mihari's plan is to concoct a medicine that changes her brother's biological constitution into a bona fide female, much to Mahiro's vehement dismay. Stuck in this predicament, Mahiro has no choice but to live out his life as a cute girl until the effect wears off—if it ever does.