[D a m i e n]

When Mion seems relieved not to have to show her tatoo i think it s pretty understandable not because she doesnt have it but because she has her pride. It would involve revieling her naked body to her friend and the one she loves (though he doesnt loves her but her sister instead) wich would hurt her feeling even more. And also because she has her pride as the heir of the yakuza familly and being naked in front of anyone is pretty humiliating for someone being used to be treated in her house with all the respect due to her stading. That is why i think she is relieved.

Spoiler:

Also Rena seems to know too much in this chapter. Sure we get to see she is pretty clever but she is showing too much confidence imo going to see mion then letting keiichi/miom alone together. something with the conversation in Mion's house was making feel that it was too well written like both girl knew the scrypt perfectely. Her voice also is not as childish as it should be. It makes me think she might have some connection with Miom other than best friend. Rena then got ride of Mion while keiichi was unconscious <-- personnal feeling only since it s made obsolete after the doll explanation and with the appearance of Mion in front of keiichi.

Using the spoiler from the book we got about a syringue being next to Shion suicide place i m assuming it was Rena since she is only one left alive that drug Shion to stab Keiichi then to suicide herself, i m not fond of paranormal/zombi theory. The appearance of Mion at the end would be an hallucination due to medecines, stress and infos given to keiichi.

Using only the anime to draw conclusion i would say that for the timeline in the deaths between Mion, Shion and keiichi attack i only see a weak state of mind for Shion since i dont want to have any paranormal activity, i only think in rationnal term. Keiichi being attack i can only think it was Shion suffering from dual personnality after what she went throught because it would otherwise involve zombi. She then attack keiichi then commit suicide. The appearance at the end is imo just an hallucination due to what he just learn + various medications like painkiller used at the hospital.

Sorry for the awfull grammar not from an english speacking country and at work writting 1 sentence here and the next 15 min later, not good at all for coherence and grammatically correct paragraph