>Niji updates (guessing they're doing baseball mascot/casting?)
Very cool teaser vid makes baseball look fun
Koushien is one of Nijisanji's biggest annual events, as well as undoubtedly their biggest annual tournament. The way it goes down is that team captains draft people (not literally, but they give their names and appearances to the baseball players) for a few rounds, which can already be chaotic in itself, then receive random extras from various branches. Then, every captain plays a season of the Eikan Nine mode in Konami's Power Pro Baseball, where they have to train their teams from scratch. Lastly, all the teams compete against one another, having to adapt to any potential fuck-ups in the training stage.
Tenkai Tsukasa and Shiina Yuika are mainstays, since they're the ones who started the tradition. Someone made a full video about the event for last year, give it a watch since it tells you everything you'd wanna know.
As for who Tenkai is, he isn't from Niji, but he was briefly part of a support partnership program with Niji. He's the leader of an indie group named BANs, which groups together Vtubers with high risk of being banned, whether due to coomer material or copyright issues. In Tenkai's case, his past also indie life was Bitou Kaiji. As in,
literally Kaiji. You can probably see why that'd raise copyright concerns.
Koushien pulls pretty big numbers each year, the finals apparently had ~200k viewers. Here's subs of the 2021 finals, which had a pretty wholesome moment when Kagami won thanks to Pomu's MVP performance, as she was in the hospital from that preventative breast cancer surgery. Her game-winning homerun starts at 2:17; once it happens, Kagami triumphantly shouts "I'M POMU! YOU'RE POMU! WE'RE POMU!"