What I can do to protect you

S1, E4: One morning, at the end of one of their usual arguments, You Keika learns about the life and death relationship between a Youmeishi and their spirit shadow, as well as the weaknesses of this from Tanmoku Ki. Along the way, Keika learns about the Tanmoku family's treasured sword (the Rakugetsu sword) as it is being taken to the family mausoleum in preparation for the pledging ceremony. He then...