I have just opened vol 2 and wow the author is so kind! (Or possibly very self aware of how reading mystery like this usually goes)
I don’t need to take any notes at all. The story&characters page in vol 2 has a good side-by side of characters and it even mentions how magic works. As I have read it once ages ago I went ahead to check how this section looks like in the future and oh boy it is great 
P.S. I find non-furigana “previously” section in full-furigana manga to be pretty cruel, but it is very good for learning. If I don’t skip it out of fear 
Upd:
Vol 2 (thoughts while reading)
Zeze should get a raise or a referral bonus. All 30-something of his classmates now have his workplace as a cheap rest area to do whatever
Hiroki is the best Veronica
Look at her, she’s so damn cool since the very beginning.
Harusumi&Takao dating has turned into a 名目 to stay together lol. Getting a girlfriend in volume one was indeed too good to be true.
Hiroki mentioned 67 people in the castle + i assume attacking Moswick soldiers? - we do have a chance of having all first years in that school to be reincarnations, not only their class
← scratch that, the school seems bigger, but it sounds like enough people for 2 classes (though only theirs is mostly missing on the assembly)
(Assuming everyone died because of that magic light pillar thing)
Damn poor Kamioka. She got attacked by magic in school and got admitted to hospital and left all alone for the night
. Minami should’ve sent her a goddamn message to at least tell her everything is fine now.
To be fair to Minami I’m reading this as a magical fantasy thing so like yeah people are gonna fight, what’s the problem. …there is a problem.
Glen was a very pretty boy, but how would you tear off your earring like that… His explanation explained nothing to me.
Sorry, did we just hint that that evil-looking dark cloud of thoughts around Minami is actually the voice of the spirits?
I just love how for the second time in two volumes MC makes a decision (live a normal life and now to not tell other people) but the story is already out of his control and things happen anyway.
Veronica had no personal boundaries and no shame even by the previous life standards
awesome 
Also I enjoy what is happening to sort of genders/relationships here as a result of reincarnation plot~
Another P.S.: oh my God that extra pages with what’s “currently” sold in Zero-Sum. Wild adapter, Saiyuuki, Loveless, Amatsuki, Dolls, Are you Alice? (Drama CD was way better than that manga), Carnival. What a nostalgic line up.