My girlfriend was brainwashed by the cult leader I hate and was NTR'd. (Kitaoka Karin MKON-118)

I went to the house of my first girlfriend, Karin-chan. A large picture of the cult leader hung in the living room, and I was told that everyone in her family except Karin-chan was a fanatical believer. Naturally, because of this, my love for Karin-chan wouldn't change. Just as things were getting more comfortable between us, Karin-chan's father returned. "We're about to perform an important ringing ceremony. Sorry, but could you please go home today?" I didn't mean to interfere with my family's beliefs, so I went home. After that, I never imagined things would turn out like that…