Post a female character who has an attraction towards and a crush on a younger male character

Kaho used to tình yêu Toya. They were together while he was in Junior High and she was a teacher. (Cardcaptor Sakura)

con trăn, boa and Luffy (One Piece)

Not sure if I'd call it a crush, but 17-year-old Ichika has a severe complex towards her new 13-year-old little step-brother Tomoya in Onee-chan ga Kita.

reiko and aiko from kissxsis

Canaria Utara from Qualidea Code.
In this case, she was a năm older than Ichiya Suzaku, but her longer amount of cryosleep resulted in him catching up to her in age.