oh great.
Chakra. The one thing Shisui Itachi was trying to find, apparently chakra doesn't exist here.. huh. Actually, chakra do but the people here barely have any, the highest he found was smaller than a civilian baby (he doesn't know if he should be disappointed or not). Oh, the bright side he had chakra, downside it was less than his previous life, about 80% less (at least it's about civilian academy size, not a civilian baby.)
So he's able to do the stuff he did in the past, cool. Also, did he mention that his father divorced his mother because of his quirk, that's just messed up (but then again, he lived in a world where killing is normal so who was he to judge?). His mother now hates him and now he's bullied because his classmates think that he's quirkless (jokes on them he beat them up instead, thank you past life talent in beating bullies).
Yeah, reincarnating into a more modern world is a pain, but at least he can be a hero now (or will he?).
Oh right he wasn't hero material