Kapowch is a kangaroo-like creature infused with Fire magic, which naturally leads to certain problems with its pouch, no matter how you slice it. First of all, even if it’s open like a real kangaroo’s, the pouch will form a pocket of heated air. This hot air will then rise out of the pouch, making it less efficient as a heat source (and for Fire monsters, heat=power) than it could otherwise be, and potentially bringing dust and shed fur along with it (right into the face, urgh).
Accounting for this, it seems Kapowch will form some method of sealing its pouch closed, but then we have new problems. As this air heats up, pressure will build inside the pouch, potentially bursting it open. This necessitates the development of some way to relieve this pressure, but then I must ask the question; what will these method be?
This question is rather important to me, as it will determine how Kapowch will execute the Fireball attack it shares with its fellow Kaijura (type of monster), and as I lack a necessary understanding of biomechanics to solve it myself, for quite some time the best thing I could come up with is Kapowch shooting bursts of flame straight up from their pouch. Obviously, this is horribly inefficient and practically useless for self-defense.
Thus, in conclusion, How Would A Kapowch's Pouch Develop?
As bukwyrm so kindly informed me, the air sealed inside the pouch will become the same temperature as the Kapowch itself, and as that air heats, it will expand, building pressure until there is an escape of air. At this point, with the pressure released and the air already heated, the pouch should stay sealed.
I'm not sure this works, however. That escape of air will likely bring shed fur and dust into the Kapowch's face, and it may allow cold air in-hot air rises, cool air sinks, so what will end up in the pouch?
The problem is further compounded by the fact that Kapowch gain and lose Fire energy, as they use or build firepower within themselves, and will naturally draw heat from the air inside their pouch when they drop in temperature. This will result in heating and cooling within the pouch, which could very well mess with the perfect seal on the pouch.
And then, of course, considering that a kangaroo's pouch is basically a biological pocket and does not seal, one has to ask how a Kapowch's pouch could gain the ability to seal in the first place! Please note, the best answer will take such problems into account.
Kapowch are insulated like a kangaroo, with fur and fat layers, and they convert ambient magical energy (mana) into
This internal heat source is depleted often; whenever a Kapowch generates or manipulates flame, it's drawing upon heat from that reserve to use as power. They can also generate heat using mana, but mana isn't static; it shifts and moves, diffuses and concentrates, so it isn't always reliable. Think of it like cell service. Because of this, a Kapowch's temperature will rise and fall, causing their air within their pouch to expand and retract, which will necessitate the development of some sort of pressure release system.
Think of it this way; the pouch is a heat battery. Whenever a Kapowch shoots a fireball or sets a fist ablaze for a searing punch, the battery gets drained. Ditto if the Kapowch is using it to stay warm. As the Kapowch grows, it becomes better at generating heat, so even if it keeps the air temperature otherwise constant inside the pouch, the air will continue to expand as heat builds inside said pouch.
I hope this helps, thanks for your input!