Where can I store my stuff before leaving?

I bought a round trip ticket that leaves from Tokyo at 3pm, so to avoid buying an extra night at an airbnb is there any place I can safely store my luggage before leaving.

Which airport are you flying out of, and which area in Tokyo will you be staying?? There are coin lockers or manned luggage storage at major train stations and airports themselves, and there are ways to send your big luggage to the airport ahead of time, but without those details it is impossible to give specific answers.

Sorry for the missing information, I will be landing at Narita International Airport

Your hotel will probably hold your luggage for you after check-out. If you want something more convenient for getting back to Narita, Tokyo Station has a luggage storage facility that you can pay for.

OP since you're at an AirBnB it is likely they will not hold your luggage.

If you are staying near Ueno and planning to use the Keisi line here is info on lockers/storage areas there.
https://www.uenostation.com/lockers-and-baggage-storage-in-ueno/

The lockers can get full.

As mentioned above, Tokyo Station also has lots of luggage storage and if you are planning to take the bus or use the NEX it is quite easy.

http://www.tokyostationcity.com/en/information/locker.html

I have specifically used the Gransta storage which is best if you have large suitcases.

You can also look into forwarding your bags to Narita from your AirBnB in advance, however I think most airports require you send your suitcases 48 in advance, just in case or at least did in the past because I ran afoul of this rule one trip, so you will likely have at least an overnight bag right before you leave no matter what.

I hope this helps!

Hi,

Check out this article on various options.
https://tokyocheapo.com/living/luggage-storage-in-tokyo/

I used Ecbo (sort of the same as booking.com, only for luggage storage in stores, restaurants etc.)
Was very happy with the service. I also found that most big lockers at the stations couldn't take my suitcase or were full. Using Ecbo will make sure have a space and is also not limited by the size of your luggage (exemptions can happen).

Christian