World building is uninspired, classes temporarily don't work like you would expect in order to set up the plot, the plot relies completely on contrived events, the MC (main character) has the IQ and awareness of a load of cracked bricks, and then the power scaling depends on how much artificial drama the author wants of a given scene.
People who worship the sun goddess wear red, the MC accuses the female lead of being a member of the sun goddess religion, and when asked why he thinks that, he points out to her blue clothing, calls it red, gets corrected, then goes "oh yeah, it's basically blue".
The plot is written at a kindergarten level... no, Dr. Seuss makes more sense. How does anyone not colour blind not know the difference between red and blue?
The MC mopes as often as possible until the plot needs to move forward. He literally repeats how useless he was, citing the same example, at least 10 times in the first 3 chapters. Moping has literally become filler content. Why is there filler only 3 chapters in?
The female characters who hate their womanizing friend choose that friend over the MC because... just because. Seriously, the girls don't even pretend to like the other friend... in fact, they don't have any motivation other than the author demands they do as much artificial, forced, emotional damage to the MC.
Female lead wants to join the MCs party, MC says no, next scene the MC follows the female lead to party up with her for no apparent reason instead of just heading for the dungeon.
Most fanfiction is written to a higher standard. It's a shame the artist had to draw for this and not another story because the art is decent.