I'm going insane trying to remember what the title is:
In the first chapter it was a guy who was originally from a Hi-Tech future fighting aliens? He then blows up everything with himself since all his comrades died and then found himself reincarnated into a fantasy world as like a 15/16 yo lord (blond haired). Then typical fantasy male lead stuff happens.
What I liked was that it was not setup for him to take over the country or something like that - it was getting sort of interesting where he meets like a Prince / heir to throne on the way while negotiating to get water from a lake from where I left off.
Just couldn't get into the plot sadly. They are cute but the second time the bottom meets up with random men who just say they know the top and then getting manipulated pissed me off too much .