Hachi is an Orange Star CO with lowered unit costs, but otherwise average stats. Nonetheless, Hachi is often considered extremely overpowered and is frequently banned from games.
Hachi's cost cut allows scrimping up for the more expensive units more doable. His price cut becomes more noticeable as units become more expensive. Kanbei's feared Md tanks typically are placed at the top of the food chain of any match, considering neotanks are rarely bought in most serious or short matches. However, they cost 19200. Hachi comes in with a cost of 14400 for a solid Md tank, that's how much Kanbei spends on a missile unit.
Another unseen advantage in this is that it makes is easier to deploy what you need when you need it, it sometimes takes too long to make a single payment of 16000 work (especially with tight funds or many fronts).
His COP is especially useful when your bases are numerous or your bases just happen to be close to the fighting. However, this is usually not the case for most 2p matches. Granted, his SCOP is hardly any better than the regular on the first day, but it really opens up more opportunities within the next few days. With his SCOP, you can make cheap mech floods that could rival Sensei's or tanks galore --
Feel the power!