I already know that "muscle power" is going to be used to ruin every aspect of this story. Can't wait for someone to try to confess to him, only for him to "misunderstand it" as a mutual love for muscles or some extremely unfunny and frustrating shit like this.
This chapter made it abundantly clear, especially in his interactions with his sister. Any potentially heartwarming moments were ruined, reduced to cheap, poorly executed jokes. This kind of writing is exactly what turns promising stories into complete garbage, just like this manga.
Though I guess I shouldn't be surprised, since this whole thing looks like the author's take on the newest manga trend, but with muscles.