Here is Eric Margolis writing for the Japan Times (just the introduction of a long article):
You may have learned that “I” is 私 (watashi). And while this is a handy all-around term to use when referring to yourself, a 2019 survey showed that over 30% of Japanese women and around 70% of Japanese men don’t regularly use it.
To make things even more confusing, people do or don’t use 私 entirely depending on the situation. While 80% of women in their 50s expected to use 私 to address colleagues or acquaintances their own age, just 30% expected to use it for people they met for the first time. Meanwhile, 60% of men in their 50s expected to use it when meeting a young person for the first time. But that percentage dropped to 40% of the time when they were meeting someone their own age.
Japanese dictionaries and resources list over 30 different words for just one in English: “I”. Every word expresses different nuances about how the speaker views themselves and what their relationship is to the person they’re speaking with. There’s わたし (watashi), わたくし (watakushi), あたし (atashi), 僕 (boku), 吾輩 (wagahai), 俺 (ore), うち (uchi), 儂 (washi), 麿 (maro) and 自分 (jibun), just to name a few. So how to know which one to use?
P.S. I would have loved to be in Japan right now, at the tennis courts watching some Japan Open tennis action.