One of the thing that I like about Japan is how much they enjoy celebrating holidays or cultures from other countries, all while having their own take on that holiday be it Christmas, Easter or any other holidays.
Halloween is no exception, from around September until 31st of October; shops, restaurants and many other places take advantage of Halloween being around the corner and start selling limited time products or having Halloween themed attractions, food, etc.
Busy areas such as Shibuya and Roppongi essentially becomes like a club minus the music, which may sound odd at first but it does make for an amusing experience.
Also, for some reason, this is one of the very few occasions where you can talk to random people, take photos and simply enjoy their company despite not knowing them.
This may not sound impressive or anything special, but having lived in Japan (especially Tokyo) this is not as common as you might imagine.
This isn’t to state that people in Tokyo are cold and don’t like to socialise, it’s just in Tokyo (or rather Japan in general ) most tend to try and respect people’s personal space and avoid invading their privacy.
I should note that aforementioned places become extremely crowded and it is very easy to get lost or separated from friends.Also taking any public transportation is a nightmare.
Another thing that I’d recommend is trying out any of the special flavours be it from supermarket or at restaurants and cafes.
They have many new items that have interesting designs and for me what I consider new flavours such as pumpkin flavoured sweets.
There are a good number of places that have many different decorations that would provide a better vibe.