18+ Doukyo Shiteiru Kensei no Onna Shishou ga Kawaisugite Mainichi Shiawase desu

Eugene Dawson, a lad who aims to get stronger, is currently training under his master, Liza Pulsandra, who is extolled as the Sword Saint. His days are spent happily with his master, who is the strongest in terms of physical strength, but whose private life is a bit of a mess. Or so one would think, but her undefended and erotic body and unconscious physical contact make something like training seem impossible...!? Can he really get stronger like this?

(Source: Kadokawa, translated)