Harima complicates the love triangle through constant bumbling, and misunderstandings among the students aggravate the situation. Harima becomes involved with Tenma's close friend, Eri Sawachika, after the pair are thrown together in mutually embarrassing situations. Later in the series, he develops a friendship with Tenma's younger sister, Yakumo Tsukamoto, who becomes Harima's assistant on a manga he writes. The plots of Harima's stories portray a Harima-like hero fighting to save a Tenma-like damsel in various historical or fantastical situations, usually in battle against an obvious facsimile of Karasuma. After the hero saves the heroine, she always falls in love with him. Yakumo's relationship with Harima causes problems with Class 2-C's student representative, Haruki Hanai, who has a crush on Yakumo, with the sisters' shared surname causing Harima and Hanai to misinterpret the object of each others' respective infatuations. Although Harima manages to engineer romantic encounters with Tenma, her relationship with Karasuma nevertheless progresses, and Harima's bonds with Eri and Yakumo grow stronger. Eventually Tenma musters the courage to confess her love, but shortly after Karasuma loses his memory. His amnesia gives a purpose to Tenma's life; she concentrates on her studies to become a doctor and help Karasuma.