First Love Monster Vol. 5 (manga)

Snooping into Kanade's diary has yielded more questions than answers for Kaho. She is no closer to learning the nature of her fifth-grade boyfriend's feelings for her, but she has discovered a rather passionate entry about another girl! Just who is "Sadako"?!! The uncertainty only adds to her anxiety, which has been steadily building since Taga's stolen kiss. As obstacles (and a crazy supporting cast) compound, will Kaho and Kanade be able to sustain their first love?