Well, it's not easy to say off the top of my head. Different manga series might number their chapters differently for the Shibuya Arc. You could try searching on manga-specific websites or asking in manga communities for the accurate chapter.
Some inumaki fanfictions could be about his growth as a sorcerer. They might show him learning new techniques or becoming stronger in the face of difficult challenges. These stories can be really exciting as they give fans a chance to see a different side of inumaki that the original series might not have fully explored.
There's also 'Inumaki's Unseen Adventures'. This fanfic focuses on the untold stories of Inumaki. It shows his growth as a sorcerer in a unique way, with some really interesting side characters and scenarios that add a lot of depth to the story.
The mystery around his speech. Since Toge Inumaki can only speak in onigiri ingredients, fanfics that try to dig deeper into how he really feels and what he wants to say but can't in the normal way are always interesting. It gives the writer a chance to be really creative in showing his internal dialogue.
The character of Inumaki himself is very appealing. His unique cursed speech ability gives fanfic writers a lot to work with. They can create all kinds of situations where his power is both a strength and a hindrance.
I'm not entirely sure as it could be a specific visual novel related to Shibuya. It might involve stories set in Shibuya, with characters experiencing various adventures, romances or mysteries in that location.