Ep 15. Onee-sama goes to Parents' Day!

As Yuzuyu's school's Parent's Day approaches, Kippei is concerned about his little sister's guardian attending the event. Kippei's oldest sister, Satsuki (also known as Onee-sama), hasn't been in contact with the family for years, and Kippei worries that her sudden appearance will cause everyone more harm than good. However, Yuzuyu is excited to see her "famous" sister and is disappointed when Kippei doesn't share her enthusiasm.

On the day of Parent's Day, Kippei watches as other students' parents visit the school, feeling more and more nervous about the prospect of Satsuki showing up. When Yuzuyu's classmates start to ask her about her sister, Kippei realizes that he doesn't even have a picture of Satsuki to show them. Feeling guilty, he decides to put his own concerns aside and take Yuzuyu to find Satsuki instead.

As they search the bustling streets of the city, Kippei begins to recount memories of his sister. He remembers how kind and protective she was when they were children, and wonders what could have caused her to cut ties with the family. Eventually, they find Satsuki working as a store clerk in a shopping center.

Kippei is surprised and hurt to see his sister in such a mundane job, but Yuzuyu loves meeting her "cool" sister and shows off her schoolwork to her. When Satsuki recognizes Yuzuyu's drawings, Kippei realizes that his sister has been keeping up with Yuzuyu's progress through news clippings and photos he had sent her. They have a heart-to-heart conversation, where Satsuki apologizes for not reaching out to them sooner and explains that she had been struggling to find her place in the world after graduating college.

Back at school, Satsuki arrives in time for the Parent's Day event. Kippei is initially uncomfortable with her presence and the attention she's receiving from their classmates, but becomes proud when Satsuki speaks fondly of their family and praises Yuzuyu's artwork. The three siblings walk home together, and Kippei sees a different side of Satsuki as she bonds with Yuzuyu, who is thrilled to have both her big brother and sister walking with her.

Overall, Aishiteruze Baby season 1 episode 15 is a heartwarming story about family reconciliation and the bonds that tie siblings together, even after years of estrangement. The episode explores themes of forgiveness, growing up, and the importance of maintaining connections with loved ones, no matter where life takes them.