極主夫道 1

This is definitely what I would tag as "crack" on ao3. It has short chapters with not that much text per page, so it is easy to follow; you won't get tired even if you have to check the dictionary often. The chapters are episodic, and the main characters are likeable. The humor leans very heavily on what is expected of the yakuza versus what actually happened (example with a spoiler - when the landlady visits the ex-yakuza husband opens the door seemingly covered in blood, swooning on the floor. What actually happened was that the cat got spooked by a roomba and spilled wine, which the roomba then proceeded to spread allover the house).

The language is pretty low N3, grammar N4-N3, but what raises the difficulty is the Kansai dialect. Not only in word and grammar choice, but also in sentence endings which can be confusing.

This was the first manga I read in Japanese, and surprisingly it wasn't too hard to get through. The most difficult aspect is the fact that it's in kansai-ben and there's yakuza slang, but once you get the hang of や = だ, へん = ない, etc., it's fairly easy to understand if your grammar knowledge is upper N4 / lower N3 imo (that's around where I'm at right now).

I'd suggest checking out the WK book club if you're not familiar with kansai-ben or yakuza slang, they have some great resources linked.