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.
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.
Maki in fanfiction usually has a fierce loyalty to her friends, especially Yuta. She is the type to fight for what she believes in. Yuta is sometimes portrayed as being a bit naive in the ways of the world outside his own small circle, but his pure heart makes him endearing. In many stories, their different personalities create an interesting dynamic, like in a story where Maki's boldness gets them into a risky situation and Yuta's calm thinking gets them out.