A fanlisting?

A fanlisting is simply an online list of fans of a subject, such as a TV show, actor, or musician, that is created by an individual and open for fans from around the world to join. There are no costs, and the only requirements to join a fanlisting are your name and country. Fanlistings do not have to be large sites (although some are), they are just a place where you can sign up with other fans.

» From The Fanlistings.org

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It came after watching when Sakuno interviews Atobe, and asks why the event is being hold that day. Atobe says something like "it wouldn't mean anything if it was hold another day". And yes, deciding this one killed me again. x_xu