One moment
Japan works back to front compared with every other destination here. You do not apply for a visa and then enrol. Your school applies to the immigration bureau for a Certificate of Eligibility on your behalf, and only once that is granted do you take it to the embassy for the visa itself. This means the school is your first gatekeeper and your financial evidence is read by them before anyone official sees it.
Japan does not publish a single national minimum for student residence status. The requirement is that you can pay tuition and living costs for the whole programme without relying on illegal work. Schools apply that principle as their own threshold, and for a one year programme they commonly ask to see in the region of two million yen, which varies by school, city and course type.
The sponsor's relationship to you, their income and the source of the money are examined at least as closely as the balance. A recently assembled figure with nothing behind it fails here as it does everywhere.
Source: Immigration Services Agency of Japan and the Ministry of Foreign Affairs set the principle; individual schools set the amount. Check the current figure on the government's own site before you rely on it; it changes, and a page is not an authority.
Dated backwards from the intake, because that is the only fixed point. The step people leave too late is marked.
Because the school submits the Certificate of Eligibility application, it carries the risk if a student disappears or cannot pay. Schools with a poor track record on that face scrutiny themselves, so they screen hard. A weak financial file usually fails at this stage rather than at the embassy, which is why it is often never described as a refusal at all.
Japanese applications ask for the sponsor's occupation, income and relationship in detail, with documents behind each. A balance that a sponsor's declared income could not plausibly have produced is the most common problem on Nepali files here.
Language schools and degree programmes want different things, and applying to a degree taught in Japanese without a level of Japanese to match invites an obvious question. If you are going via a language school first, say so plainly and show how the two steps connect.
The Certificate of Eligibility takes months, and it happens before the visa rather than after it. An application started at the timescale that works for Australia will miss a Japanese intake entirely.