At the beginning I thought it would be a story about a powerful being destroying earth and everything that comes with it.
Logic, methods, execution and how humanity would react to that. If in process someone like Ah Leesu appears he'll try to correct people instead, if they continue destroying Earth in spite of that he'd act accordingly. More of less don't mess with earth or I'll fuck you up kind of story.
Maybe Mc acting as an ultimate police on behalf of the planet. As a result humanity would become a better version of itself, full in on renewable energy as an example. Driving force for that is existence of Mc.
Instead I got a missed opportunity, love story on steroids. A conscious virus appears and it was either created by humans or some natural thing that's made to act like Mc was supposed to - extinction, don't remember and it doesn't matter. It was used as a means for Mc to grow.
Cancer lady had little to no impact on anything if you made the story 42 chapters instead, nothing would change, less people would end up dead, that's it. Sure her involvement showed the lows that people would go down to in that situation, but why, it's a love story, stick to it.
And the main thing, humanity learned nothing, to them 2 monsters appeared, killed people and as far as an average joe is concerned Ah Leesu, one of the monsters, is still alive. The Steer is dead, but do they know that? Why was she Steer? What is Steer? How can people be sure she's still not Steer pretending? Mc saved her but I'd argue her existence from this point on is pretty miserable and she always has a mark on her back.
They didn't even show cancer lady's death.
Overall I consider this a waste of time.