Also known as: やるっきゃ騎士
Yarukkyakishi (やるっきゃ騎士), often translated as "The Do-or-Die Knight," is a Japanese manga series written and illustrated by Michiru Norizuki. It originally ran in the 1980s in Monthly Shonen Jump.
It is best described as a "sexy comedy" or ecchi series that blends school life, slapstick humor, and mild eroticism, which was a popular trope in shonen manga of that era.