i have a feeling, that they have died and before he came back and erased the memory's of them so he would not feel sayed. like how he did when he found out about sage
page 5 : so oji-san and ice girl spent the night together and slept on a same bed , so naughty , and elf girl was staring at them for the whole night , lol .
page 20 : saying her name can make her cumming , lol .
page 29 : yo oji-san , destroying an ancient , cultural structure is a very serious crime : https://en.wikipedia.org/wiki/Cultural_genocide
Maybe some previous reincarnator or transmigrated person wrote some sort of trashy scribble about sega, the saturn, the megadrive/genesis or one of sega mascot somewhere on this building ?
Seing how the author loves trolling with templates and triggering his readers, I expect some really violent anger baiting at the end of this manga...