And volume 4 finished! So, yeah, I'm up to date.
A little spoiler:
Sou's new skill was useful, even if we still don't know everything about it I guess, and the conditions for his strongest Art are revealed. (Seriously, if it wasn't Sou, who could even use this art properly?)
In the end, I liked this novel way more than I thought I would at first. Really good humour, likable MC (love his reactions and mood swings), likable characters (変人), and the story progresses at a good pace. If the LN get a good illustrator, I think I might buy it when I'll be in Japan.
So, for my next WN I'm hesiting between マジックイーター（Magic Eater :通称ME） 〜ゴブリンデッキから始まる異世界冒険〜 and 俺の現実は恋愛ゲーム？？ ～かと思ったら命がけのゲームだった～. Well, considering the number of chapters and that it's finished, maybe 憑依無双 ～何度殺されても身体を乗り換えて復活する～ too. (Those three are the WNs with the least chapters in my current reading list, not counting WNs with rare updates that I put aside, like 異世界旅行は落ち着かない for example)