1. Spend a day people watching at Yoyogi Park: Although you could spend any day here, the most exciting and interesting, from an observer's point of view, is Sunday. The park is enormous -- a former airstrip, army parade ground and site for the Olympic Games in 1964. All sorts of people gather on Sunday, from jazz musicians and jamming guitarists, to martial artists, singers and jugglers. This motley ensemble of characters is fascinating to watch.
2. Watch the local giants: What better way to immerse yourself in Japanese culture than by taking in the national sport? There are few spectacles more intriguing than the sight of two barely-covered behemoths squaring off against one another, each with the intention of taking his opponent down or bundling him out of the ring. Sumo is a source of national pride in Japan and the wrestlers are viewed as heroes. The next major tournament in Tokyo, visit the Sumo website - Sumo.or.jp for more info.
3. Marvel at Japanese fashion: When it comes to clothes, Tokyo is beyond cutting edge. The colors and designs are like something from another planet. Head straight to Harajuku (Harajuku station on the Yamanote line) and spend the day seeing what sorts of new threads you can spot. Close to the station are Takeshita-dori, where you'll find many independent designers stores, Yoyogi Park, where you can spot gaggles of Gothic Lolitas, and Omotesando, for high-end fashion outlets.
4. Get electrified in electric town: Akihabara, located close to the Tokyo railway station, is the place to go (in the world) for electronics. You'll find absolutely everything here, from state-of-the-art technology in the Laox store, to secondhand stuff in the back streets. Akihabara is also a hobbyists' paradise, with large communities of manga and anime lovers hanging out.
5. Tackle the tuna in Tsukiji: If things start smelling a little fishy, don't panic; you've probably just found yourself in the world's biggest fish market. Tsukiji Fish Market is home to every imaginable type of seafood ... and then some. The food is excellent, and you can stop off for a bowl of ramen or a plate of sushi while you're there. Be prepared to get a little confused, particularly if you're trying to decipher a map. In terms of cultural experiences, it doesn't get much better (or bigger) than this.
Check out hotel availability and special hotel price at Agoda.com - http://www.agoda.com/asia/japan/tokyo.html
Gokouun o inorimasu! (good luck)