She sits there and understands that Shuichi is partially a demon and within him is the spirit of a very old one that grants him powers beyond her imagination, and that cute girl he brought home is technically the Grim Reaper, but he'll call her the one who guides the deceased to the next life. She's just totally cool with it. 

Sigh... well, so long as you know it'll be an underwhelming response from me. I'll try to get something up tonight if my inner critic doesn't tell me that I'm in over my head.