>>23467756
Lelouch's resurrection is the penultimate stage to the finale of chapter 2. The involved characters have some fun interactions with Re;surrection villains. Kallen has had like 5-6 different outfits so far.

>>23467857
Sandrock has 3 so far, same with Deathscythe - don't know if you can unlock a new one for them later.

>>23467811
Not a lot - there's early acknowledgement when Takuma meets Jin in the story.

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I'm pretty surprised at the playable Delta characters. I thought it'd just be Hayato & Mirage, but there's also Arad, Messer, & Chuck.