Tokyo is best understood not as one city but as a series of dense centres strung along the Yamanote loop line. Shinjuku, Shibuya, Ikebukuro, Ueno and Tokyo Station each have their own character, scale and reason to visit, and the loop connects them in roughly an hour. Trains are the whole experience: punctual to the second, clean, and comprehensible once you have an IC card, which you tap onto almost every line, bus and convenience store in the country. The city rewards specificity over breadth. A single neighbourhood explored properly - Yanaka for old Tokyo, Shimokitazawa for second-hand shops, Kagurazaka for its lanes - will leave a stronger impression than five landmark stops in a day. Cash still matters in small restaurants and at shrines, despite cards being accepted almost everywhere else.
When to visit
Late March to May, and October to November. Summer is hot and humid; the blossom and autumn seasons draw large domestic crowds.