Here you have the reason why Kei carries his current book always with him - it's the typical case of "I can't risk anyone looking inside while I'm gone." That, and he likes having it nearby in case something comes to mind he needs to write down. Why doesn't he just use his phone for that? Well, while this is a quite advanced world, there are still plenty of book lovers around who prefer to read - and in this case, write - books the old-fashioned way.

The topmost panel shows my very own dedication in trying to make the school look more lively by having more people around. Woah, the last time I drew Minoru (on the left) was in 2013... ;;

This is your last chance to read Hyoukyo Mirror in case you haven't yet and don't want to be spoiled - the next page will show someone whose appearance might confuse you otherwise.

While Taku and Kei are walking they come across another classroom in which two other students have a lively conversation we don't get to hear.

Taku: "You sure read a lot."
Kei: "Oh, the books I carry around with me aren't for reading. They're for writing."
Taku: "So when you say you 'finished' the old book, you mean... you filled every single page?"
Kei: "Yes!"
Taku: "... Okay."

Unfortunately, the happy mood vanishes as Kei brings up a different topic.

Kei: "Umm, soooo... Did you tell someone about what happened in the storage room?"