Hmm i think author or artist made a mistake with how they handled this arc. The weight of the general's death is not that heavy because of the 2 month training time skip. If the author/artist at least give 1-2 chapter of what mc had to go thru in 2 month training and his relationship with the general, it would have had a better weight to it. Now it really just feels like a cheap plot just to give mc a reason and motivation to go against the 3 clans.
Im kinda losing interest now because theres also a lack of hook. Him joining force with the girl is not enough because she dont have much power (hidden clan backing) unless author havent shown it. I would guess that the plot is that all the small and scattered clans will join force to fight the 3 tyrants but for the intro arc to fail a good setup and feels a little rushed for me is a big meh. It feels like the next arc would instantly jump the mc against one of the tyrant but i would do another guess and say that the 3 tyrants should be on cooldown from the fight against the general.
... now im questioning why the small clans lost against the 3 tyrants when the general could put up a fight against 3 of them albeit while using his life force. Should give this one some more chapter chances before deciding to drop or not.