Shiki is a 24 episode horror anime series from 2010. It's numbered 1-22 and there are 2 midquels, 20.5 and 21.5 that came out in the OVA release in 2011.
It is implied that Akira Tanaka took an Offscreen Bath because he has a flashback of telling his parents about his suspicions about a new mansion, and his mother (Sachiko Tanaka) tells him to take a bath.
The second ending theme of the series, which starts on episode 12, features five of the main characters bathing in pools of a translucent red liquid which is probably meant to be blood.
Probably Kaoru Tanaka
Probably Ritsuko Kunihiro
Natsuno with Tohru Mutou