Responses

Grandpa is Kotarus grandpa, Saki finds out from Kotarus parents that grandpa apparently died the day he shot down his offer to hang out, Saki was devastated thinking he could have prevented Grandpas death if he wasn’t self absorbed in his own pain. He then was also feeling very guilty about not having told Kotaru, and still blames himself. But I think Kotaru was like, no he shouldn’t feel guilty because he didn’t die that day he just collapsed and then died a few days after at the hospital. Big mess lol, sorry if this made no sense ( ̄∇ ̄")
I'm just going with the flow now, not questioning anything HSHAHHA I kinda forgot what was the issue with the grandpa