I already talked about this in my review for season 1 so I'll try not to focus on it, but a working knowledge of all 6 main visual novels by the company Key is necessary to watch this. All of them have anime adaptations, if you've seen those you're probably fine, but there will still be some jokes that leave you scratching your head and checking wiki articles or vndb trying to figure out who such and such character was. This is a show for people who were already big fans of Key's work, and trust me, if that's not you you're better off justenjoying something else rather than spending the time doing your homework first.

One more note on that before moving on with the review is that they've included Angel Beats to their line-up this season, which is notably an anime original story. But Key made a visual novel adaptation of the anime back in 2015, hence their inclusion. Honestly the story seems like something they'd do anyway, and even has a lot of parallels that can be drawn with stuff like Little Busters and Rewrite.

Seeing all these characters together and the way they play off of each other is really fun. I love the running joke where they group characters that fall into similar archetypes together and have them complain about their pigeon-holed position in their respective story. The meetings of the protagonists club, the main heroines club, and the rejected heroines clubs are all hilarious. I love how blatantly salty some characters are at what happened to them in their stories and how matter-of-factly they talk about traumatic moments.

The framing device that it's all tied together as a presentation from the Planetaian girl to Ushio and all the in jokes about this being a convenient universe where anything can happen, there's just so much meta humor you start to get confused about what's a joke and what's serious. They masterfully use the dramatic climaxes of the individual stories as punch lines and undercut any seriousness with some goofy misdirection. It's just the sort of humor I like.
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