This is crazy! A jab of unknown liquid for 150,000 yen (roughly 1377 USD). If somebody spends his/her hard earning money for this, he/she not only waste the money but also risking his/her own life injecting that thing. Even if it is a real thing, you need to know that most vaccines need two shots, where does one find the second shot afterward? Another 150K yen for another unknown liquid? Further, vaccines need to keep at certain temperature. If it is a Pfizer or Modena, the vaccine has long spoiled before it would arrive at buyer's hand.
The bottom line is: if you don't have access to formal vaccines, just stay at home.