Usually, for most of us, getting a local number is not necessary. However, if you absolutely need one, go to Mobal.com. We are traveling to Japan tomorrow and I signed up. The surprising thing is the day before, the phone we have registered for the Japanese number suddenly popped up with a notice about a new eSIM. Fantastic. Easy to set up.
Why would you need a local number? In case you are making reservation for some place that requires a local phone number. Other than that, you could of course us an IP phone app to call locally like Skype.