[POTENTIAL SPOILERS]
A profoundly impactful manga, one that moved me to tears on several occasions funnily enough, and yet left me grappling with conflicting emotions, especially regarding its conclusion. I will yap a little bit, ignore this message since it's not that deep anyway.
I personally disliked, no, hated the ending. Picture this, the author(s) dangle a thread of hope before us, only to mercilessly unravel it just a few chapters later, repeating this cycle of dashed hopes until the very end. It's akin to being teased with a flicker of light in the darkness, only to have it snuffed out again and again. As one of the characters said in the manga, readers want hope. We seek refuge from the harsh realities of our world by reading books or doing things that we like doing, we do not want a constant reminder of its cruelty even in our free time.
However, the messages that this manga sends you -- disregarding the controversial topic it might have brought with its age gap -- time, is the real deal. We just don't have enough. Or, to look at it in a different way, we have exactly as much as we need but it's not guaranteed that we'll use it correctly. It's never too late because we don't know what too late is but it will be too late if you put everything off until tomorrow.
My judgment of the ending is undoubtedly biased, colored by personal experience. I harbored a genuine desire for our protagonist, Nijima, to find the happiness that eluded me and countless others. I wanted him to obtain happiness that I, or many other people in real life could not obtain. At the very least wanted a fictional character to be happy, can you believe that? But well, you realize that the characters are pretty engaging if you somewhat resonate with them, or understand them. Sure, while some may argue that Nijima has already achieved happiness, in my eyes I perceive him as a tragic figure trying to look strong in front of others while suffering in silence.
I liked the manga overall. I just despise the ending, that's all.