"Three million in one month" is almost a losing game from the moment you aim from zero.
Starting from zero and aiming to make 3 million in one month is realistically more of a gamble or leaning toward gray areas or illegal routes, so that line of thinking is already off track. The only legal options that are still somewhat viable are when you already have skills and a client list and you can boost with: 1) landing 3–4 high-priced freelance projects at once (engineering, marketing, video, consulting), 2) going after sales of high-priced products on commission, 3) quickly cycling inventory with relatively low risk through resale/wholesale with an initial capital of about 1–2 million yen—i.e., the patterns where “people who are prepared boost.”