Inran de Seijun

1-5. Inran de Seijun (淫乱で清純); Magazine Cyberia vol.052, 054, 057, 059, 061
Beautiful and intelligent, Takeuchi is a model high school student. But she has an enormous secret: what she prefers most in the world is to masturbate! Now an expert on the subject, she was convinced that no man could ever give her so much pleasure and was not interested in the opposite sex at all. But that was before she fell in love with Mizoguchi, the vice-president of the students' council. Will she succeed in hiding her true nature? Under her air of a goody-two-shoes, Takeuchi is a real pervert... and has more in common with Mizoguchi than she imagines!

(Source: Hot Manga, translated)

6-11. Nozoki Danchi (のぞき団地); Magazine Cyberia vol.063, 065, 067, 069, 072, 076

Note: Nozoki Danchi was originally serialized under the title "Voyeurism" (VOYEURISM). The volume only compiles the first 6 chapters.