However hidden behind built-up banks it may be, the Sumida River is not exactly a "back street." But as it's said that one of the best places from which to view cherry blossoms in Tokyo is from a water bus plying the river, I resolved on a reconnaissance better referred to as a "back stream" story.

The ticket office of the Suijo (literally, and reassuringly, "above water") Bus is perched on the eastern side of Azuma Bridge, two minutes from the Ginza Line's terminal at Asakusa Station. In the carny atmosphere of caramel popcorn, hot concessions and various water-bus trinkets for sale, I ticket up for the next boat out.

There are 11 buses on rotation (12, if you count the nine-seater rescue boat), offering several route options. I've just missed the sleek, futuristic Himiko — designed by manga artist Leiji Matsumoto — which slinks out with a flock of yellow-capped elementary school students aboard. As the Himiko only offers direct Asakusa-Odaiba runs, and I want to get off at Hama-rikyu Gardens and Hinode Pier, I'm happy to wave them on their way.