Shape Moon: a Fateful Night That Begins with Tsukihime

(Type Yuezong) (no system) My name is Nanaya Nagi... Oh! Wrong! It should be called Ryogi Nagi now! Since I was 14 years old, I have been traveling around the country with my teacher Aozaki Orange, but now my step-sister is married and she has given birth to a niece! Then you have to go back to your country and have a look! As a result, I met a powerful thing just after I came back... He obviously chopped her into pieces! Why can he appear in front of me the next day and say nothing? "You must take responsibility for killing me." And who is the True Ancestor who degenerated into the Demon King? Until four years after everything was resolved... I was traveling around with my girlfriend, and as soon as I got off the plane in Fuyuki City, I caught an inhuman being. Ryogi Nagi opened his eyes of death and took a glance. Oh, it turns out her name is Medea... Wait a minute! I've set a tight deadline! Spirit base? Spirit core? I see! You've come here, it's not easy to come across such an interesting thing! Then you must participate to have some fun!