Bio: Seiko comes from class three is one of the new mikos who make up the Miko Council. Seiko like all the girls has a fun and serious side. She tends to be outgoing over all. In some ways Seiko has a bit of an authorative role in the series. Although she is not the leader, she could easily be one from the way she acts. Seiko seems to be closest to Chika as the two are together a lot. My guess is the two of them hanged out together in school for a bit and eventually decided to become friends and hang out together a lot.
Opinion: She's extremely cool. She just has a take charge attitude. Like I said before, she seems to be more of a leader than the main (Yuzu) herself. I also like the ah sub plot about her attack's name.