Ako Suminoe  

, 住之江 あこ

Ako is an older twin sister who can be distinguished from Riko by her hair clip. She possesses a dependable and rational personality, yet can also be gloomy, capricious, and somewhat juvenile. In contrast to Riko, she carries herself differently and excels in cooking, which she learned to assist her mother with household chores. Ako is proficient in consuming alcohol and sometimes employs it to subdue Riko so that she may enjoy the more lively Keita's company. She harbors secret desires for Keita and frequently plans to seduce him, even concealing pornographic magazines in her room. At school, Ako serves on the committee but often misuses her power to bully Keita.