A slutty slave life where her older girlfriend keeps her nipples stimulating until she ejaculates

I'm an ordinary college student everywhere...I'm the only thing that makes me different is that I live with a girlfriend who is not as beautiful as me and has a great figure. Her Ichika is very kind. But... there's something I've been interested in lately. That is... she loves Boku's nipples more than Boku's... She doesn't care about Boku's will, and even when she sleeps or wakes up, she's tingling... Boku's nipples live as Ichika's slave...