why blood cells and not try and upgrade his Genetics, or DNA? Get to kyptonian/Czarnian levels. Or is that not possible? Limited by his own knowledge? MC needs to learn all Umbrella Genetic Manipulation knowledge.
personally, I'd sit down with mom and dad, Explain that I'm a reincarnator, (state everyone is, but most lose memories, hence Deja Vu)
Then I would explain concerns about the world & umbrella. Preparing for things to hit the fan while enabling myself and my family the best chance to survive.
Would it be possible to reach the level of garen from mystical journey in the first world where his aura takes form he has a similar cheat or would it be to suparnatural ?:)
...I feel like this is rushed...need to sleep before checking what's making me feel so wrong. Major headache. Had to revise this chapter 4-5 times in 3+different directions. I chose bonding in the end and not rush a future meeting...he's 1 year old ffs.