It's funny people think better of Kazuya here even though he acted like in the main story. The only different is we didn't get to read his thoughts this time but Sumi's.
Also I hope this side story also gets released in the west.
That's the place where the Mom pushed Sei off. The place where she pushed Shige was way up in the middle of a forest in the mountains. Shige doesn't know this place holds special meaning for Sei so this is clearly Sei dreaming.
I prefer Fujimoto's way of showing rather than telling 100X over the manga who spoonfeed people everything through big textboxes. If I want that, I read a book. Also this way, some things stay more nebulous, which is fun to discuss and make theories about. I'm sure in the end, I reread...
@2ND Well, that's true XD But she could try work as web designer or video editor from home. I think that might be a good way for her to start out rather than throwing her into masses.