You need to choose a best-girl (bottom bitch) in order to acquire the set! The #1 manages the others, otherwise you're stuck dealing with plots/tests of increasing drama and decreasing rationality, like dressing all alike and guessing who is who....
1. Ichika is the one ussualy called "fuutaroukun"
2. "Test again" because fuu failed to recognize her at the bath
3. Process of elemination
2. Yotsuba tend to tilt her heard
It's simple the always look happy is yotsuba, the one that makes remark is Nino, Miku is the silent or hard to smile face.Itsuki is a fatberg just deal thith food and you find her. Ichika is the last one.