I'd like to say it's smart of him to infiltrate enemy base like that but true, considering Hayama I doubt he has a plan beyond that point lmao, it's always the plot that saved him.
20 mil JPY is about 130,000 USD which in japan is still way too much money for the average university student to have, that amount is equivalent to what japanese retirees are advised to have saved by their government in order to have an adequate post-retirement life