A true ladies' man, Amachi is the perfect gentleman, with a face to match. He is Manaka's rival for Toujou's affections, although he does not pose too much of a threat (It's apparent that she prefers Manaka). Like Okusa, Amachi has herds of girls flocking to him, and he seems to have a compulsive necessity in helping women in need. After meeting staunch resistance to his approaches on Toujou, Amachi gives up his horde of girls as a sign of devotion to Toujou, but later returns to them after news breaks out that Toujou is not going with Manaka or him to the final school festival. Amachi once challenged Manaka to a swimming race, (which he won of course) but Toujou dived into the water to save Manaka from drowning from exhaustion, despite the fact she could not swim. After seeing Toujou in her swimsuit, he had a nosebleed (comically) that was so bad, that Manaka had to walk her home instead of him. He also managed to recognize Toujou even with her hair braided and glasses on, which Toujou's cram school friends took to mean that he truly did love her.
In a last bid attempt to capture Toujou's love interest, and clear Manaka from her mind (which he believed were restricting her talents), asked Toujou to take off her glasses before attempting to kiss her. However Toujou, still in love with Manaka, "escaped" from this situation, leaving Amachi behind.