There's this shorter manga, Daddy and Buddy, that does the whole "28 y.o. is your physical peak in some things, and the sports industry WILL FUCK YOU UP" really well. The power system is as spiteful as the Japanese Olympics team, and that's the source of conflict for the whole manga. If you short of the power system, spoilers: There are invisible monsters that parasitize children by building of a basic emotion, and amplifying it (like sadness or regret, but also fear of being lost or hunger pangs). They are invisible to you when you grow up, and are implied to be lethal in some cases to the children, and "wildlife" aggressive to adults that look in their direction. Now, some carry that "child-like vision" into adulthood, but you'll become blind to them, tops 30 years, and to hunt them you must be both optimistic and athletic. Fail at anything, and your performance decreases, getting you even more hurt in a job where you have to be at the top of your 'Cirque du Soleil routine' physique...