Sacchin

Satsuki Yumizuka (弓塚 さつき), also known as "Sacchin" (さっちん, her nickname, a contraction of "Satsuki-chan"), is a student at Misaki Municipal High School in Tsukihime. Satsuki's crush on Shiki began when her sports club was trapped inside a room after-hours in the winter, freezing cold as they had all still been in their gym outfits. When it seemed as though nobody was going to come and rescue them, Shiki suddenly appeared and freed them by cutting the lines of the lock. She developed feelings for him from that moment onward, but he had never really noticed her.