You might get more out of it by focusing on where to shop rather than what to buy. Tokyo used to have many interesting small shops, the way other major cities did before online shopping. Going around to brick & mortar shops now is time consuming and mostly not worth it if you know what you want, because the selection is so much better online. For many things, there will be importers operating in your country. For example, www.jetpens.com does a great job bringing less expensive stationery items into the USA.
I would focus on the unique shopping experiences to be had in Tokyo. If you are into fountain pens, Shosaikan[1] should be near the top of your list. This thread covers more locations.[2]
For housewares and small tools, the best browsing is Hands (formerly Tokyu Hands). I love the aesthetics of Japanese home and office goods, but the more interesting things are generally not exported. I have many things that were inexpensive but unique and very nice to have. Just one example, the Japanese "pipe pillow".[3]
[1] https://tokyostationpens.com/2020/04/21/shosaikan-a-virtual-...
[2] https://www.fountainpennetwork.com/forum/topic/368781-founta...
[3] https://commons.wikimedia.org/wiki/File:Japanese_Pipe_Pillow...
Hand tools.
Ratchets: Ko-ken. KTC. Tone.
Sockets: Ko-ken, KTC
Wrenches. KTC. Asahi, Top, Lobtex
Pliers: Tsunoda, IPS, Engineer Screwdriver: Vessel, Anex.
https://www.reddit.com/r/BuyItForLife/comments/1eeby2w/japan...
From an environmental stand it's great because it's reusable.
From a writing stand it's an amazing feel every time I write.
It brings me so much happiness each time I use my daiso rice scoop or getting a tealight out of the bag I bought my fountain pen in! and ofc chopsticks because they really do the best ones.
If your buying pens don't forget to stock up on ink!
If I'd had more money at the time I would have bought better quality but the fact that some things were from the 100y store and are still better quality than stuff bought here says a lot!
Also the second-hand clothing stores are just incredible to peruse
They’re pricy, but it’ll last forever and be wicked sharp. You’ll need it for when you want to prepare delicious meals to remind yourself of the trip ;)
Also, just about anything made by Mitutoyo is very good quality if not counterfeit.
There is also the Pokémon Center buildings toy store for rare gifts.
Have fun, =3