I would like to make romantic surprises for my Girlfriend during our trip in Tokyo, e.g. a Helicopter night ride, a dinner up on Skytree, Tokyo night time river cruise etc.
What would be other recommendations?
1. Tokyo Disney Sea
Tokyo Disney Sea's night view is amazing.
They have a huge artificial lake in the center of the park and the area is built like Venice. The reflected lights in the water are just beautiful.
2. Roppongi Jazz bar
In Grand Hyatt Roppongi, there is a luxury jazz bar "MADURO". You can have delicious cocktails and listen to great Jazz performance. Sofa are so comfortable and English language is perfect.
3. Night view from Roppongi Sky deck or Skytree
Very standard but recommended! Another option would be Tokyo Tower, but I recommend seeing Tokyo Tower from a higher point of view :)
4. Sunset at Odaiba Marine Park
It is hard to find a beach in Tokyo, but here it is in Odaiba. No doubt it's romantic with the sunset!
5. Surprise message at street screens
There are many screens in major towns in Tokyo such as Shibuya and Shinjuku. Some of them accepts personal messages with certain amount of fees. It will sure surprise your girlfriend!
http://www.hapiba.com/project/message-vision.html (website is in Japanese)
6. Planetarium Bar
This hidden bar in Shirokanetakanawa, near Meguro, is a planetarium themed bar.
Stars are displayed on the ceiling of the bar, together with comfortable sofas, creating a romantic and relaxing atmosphere.
7. Cruise dinner / lunch
There are few companies running cruise dinner / lunch plans at Tokyo bay. Ships leave either from Odaiba or Hamamatsu cho.
I'd recommend dinner. Seeing the Tokyo cityscape from a ship will be unforgettable experience!
8. Writing message on the building windows by room lights.
I could not find information how to exactly do this, but there seems to be some buildings that allow displaying personal messages like this:
9. Flash mob
Apparently, this is getting bigger in Tokyo and there are few companies doing this business.
10. Sunrise at the summit of Mt. Takao
If you prefer to be in nature, Mt. Takano is only 50mins train ride from Shinjuku. Tokyo city view from the top of mountain changing color from dark to orange must be beautiful.
Good luck on surprising your girlfriend!