>>281363760
Someone smarter than me could probably elaborate on some of the Buddhist themes and such (kind of explicit since the MC becomes a Senju Kannon) Personally I think it's "intellectual" because it's a high wisdom work, delivering straightforward but very effective character beats for a lot of characters. I don't know if intellectual is the best word for it but these works convey the human experience with tons of maturity, wisdom and insights, through convincing and well developed characters.
Tons of subtlety too. There's a revenge plot in there, it's not the main point of the story but even with it being minor it's handled in a very nuanced way that goes beyond "revenge bad" or even "revenge good".