[Sangetsu]

2000 Euros... That will be for airfare and hotel for 2? To Tokyo? For 5 days?

It's possible, but may not be easy. The cheapest you'll find a three star hotel for in Tokyo is probably around 15,000 yen per night. I'd recommend the Prince hotel in Shinagawa. The rooms aren't bad, the location is great, and you should be able to get one for less than 10,000 yen per night.

The Prince hotel is on the Yamanote line adjacent to Shinagawa station. The Yamanote line passes the places of most interest in Tokyo, such as the palace, the museums and zoo at Ueno, Ikebukuro, Shibuya, Harajuku, etc. You can get to Odaiba by switching from the Yamanote train to the Yurikamome train at Shinbashi station, which is between Tokyo station and Shinagawa station.

Good luck.