Nothing too direct other than Persona, I suppose. I'm a fan of the Nasuverse, but I'm not savvy enough to run anything in it, so there's some inspiration drawn from concepts in there (notably the Earthmind/Gaia expy). The death aspect of it just seemed like an interesting approach, to look at the way something/someone died as part of their abilities rather than 'Yes I am dead and now I have some unrelated abilities because of it'. There's bits and pieces of inspiration from other work if you squint, like Soul Eater a friend pointed out.