Top 5 Ecchi: anime with lots of fanservice

High School DxD – The story of Issei Hyodo, a perverted student who is reborn as a demon to serve the demon princess Rias Gremory. Known for its abundant harem fanservice and supernatural combat.

To Love Ru – Romantic comedy about Rito Yuuki, a clumsy boy who gets involved with the alien princess Lala. Notable for its embarrassing situations and risqué scenes.

Prison School – Five boys are caught spying at school and punished by being sent to the student “prison,” triggering extreme scenes of erotic comedy.

Monster Musume – Kimihito takes in several “monster” girls (lamia, succubus, etc.) into his home as part of an exchange program. Each creature has torrid love affairs with him, creating provocative situations.

Sekirei – Minato Sahashi becomes the “Ashikabi” of several supernatural warriors (Sekirei). The series mixes combat and fanservice, as the Sekirei are attractive women who must kiss Minato to prove their bond.
These anime are characterized by light plots where ecchi (sensual content) takes center stage. They offer fun for those looking for spicy humor and attractive characters, and have been referenced in fan service worldwide.