Ah I swear to god, the author probablly made him 'lose' the muffler just so shikimori can return it and look cool, because he hasn't been able to draw her like that in a while.
I've liked this manga a lot so far, but this arc is pretty pointless imo, isn't going anywhere, and is too long, kinda boring.
The story has been going nowhere for a while now.
I know it's a highschool slice of life manga, so not everything needs to add something to the story, but that is still holding back the progression a lot.