According to a local Japanese the islands of Odaiba were artificially build in the Edo Period (1850). Because the Americans wanted to go to China and needed a harbor they asked Japan for a port. At that time though, Japan was still a closed country and didn’t want to have any commercial agreement with any other country except for the Dutch people. The reason was because Japanese didn’t want Catholics into their country and since the Dutch were focused on merchandising only, they were allowed to enter Japan. Because it was foreseeable that the Americans would break through Japan, the island fort (“Daiba”) has been built and equipped with canons. However in the end the Americans still got easily through. This can be partially verified with Wikipedia.
Today there are some very cool sights there to see and the beach of Odaiba is very chill. It also appears that it is a place where many festivals are held. In 2020 the Olympic participants will be reside at Odaiba.
My first checkpoint was the Miraikan Museum. The entrance fee was only 620 Yen and it is really worthwhile there. I stayed for 3.5 h and would say i could have stayed there for at least another hour. Although the museum tries to involve kids as well it is a science museum to begin with so that it might be boring for kids under 16 years old.
Some of the cool sights include a huge Gundam figure, which “transforms” at specific times. Although transforming would suggest too much – it only changes color and moves the horn part.
Another interesting sight is a mini version of the statue of liberty which was initially only erected to pay tribute to Japan’s tie with France in 1998-19991.
The rainbow bridge is also worth mentioning as well. You can pass the bridge in the afternoon by foot however i suggest you to not stay too long because many cars are driving right next to you. It is open to pedestrians till 9 pm (in summer) and offers a great night view.
The last thing on the list to be mentioned is the beach. Although you are not allowed to swim the beach offers a nice place to have a pick-nick or a silent spot under the night sky with an amazing view over Tokyo’s colorful lights.