You can find those letter openers that are shaped like miniature Japanese swords, also known as "katana letter openers," in many places in Tokyo. Here are a few places to check out:
1. Akihabara: This neighborhood is known for its electronics and anime culture, but it's also a great place to find unique souvenirs. Check out the many shops selling anime merchandise and collectibles, as well as the Don Quijote and Yodobashi Camera stores.
2. Samurai Museum Gift Shop: The Samurai Museum in Shinjuku has a gift shop that sells a variety of samurai-related items, including katana letter openers.
3. Tokyo Hands: This department store chain has multiple locations throughout Tokyo, including in Shibuya and Ikebukuro. They sell a variety of household items, including letter openers, and often have a section dedicated to traditional Japanese crafts and souvenirs.
4. Kappabashi-dori: This street in Asakusa is known for its shops selling kitchenware and restaurant supplies, but it also has a variety of souvenir shops. Look for shops selling traditional Japanese swords and knives, as they may also carry katana letter openers.
5. Tokyu Hands: This department store chain also has multiple locations throughout Tokyo, including in Shinjuku and Shibuya. They have a wide selection of stationery and office supplies, including letter openers, and often carry unique and quirky items.
These are just a few suggestions, but there are many other places in Tokyo where you can find katana letter openers. It's always a good idea to explore different neighborhoods and see what you can find!