Ep. 17: Shinobu Time, Part One
After returning from his trip through time, Koyomi comes back home and meets Mayoi, finally returning her backpack. They suddenly come across a mysterious being that starts chasing them down. The two manage to escape when they meet Yotsugi who flies away with them to safety. After stealing a kiss from Koyomi to repay for her help, Yotsugi flees, leaving Koyomi at the mercy of a furious Shinobu that appears soon after and to calm her down, Koyomi kisses her too. With Mayoi still unconscious from their predicament, Koyomi inquires Shinobu about the "darkness" entity they saw and she claims that she had seen it before during a trip to Japan 400 years before. She also claims that it will cause the destruction of the entire city if nothing is done about it. (Source: Wikipedia)