I recently read the article How to get Japanese phone number от mobal https://www.mobal.com/blog/travel-talk/the-japanese-phone-number-and-why-you-might-need-one/ from Mobal and was pleasantly surprised. It turns out the process of getting a Japanese number isn't as complicated as it seems. The text explains in detail what documents are needed, how to choose a plan, and whether SIM or eSIM is better. I liked the article's human tone: no dry instructions, everything is simple and clear. I highly recommend it.