Shinobu managed to become friends with Tomioka. They both began hanging out. But one day Shinobu found a interest in the flame pillar. They both were getting closer until Shinobu had a fight with Giyu. And soon Giyu found himself with a girl. Later Shinobu found herself in jealousy and regrets her decision. Read to find out rest.
this is a crossover
Kaguya, Muzan-parents
Sebastian, Kagaya, Tsutako, Momo, Levi, Marinette, Giyuu, and Sasuke-children age order
not my au can't remember creator