There are many reasons for heading across the Sumida River to Tsukishima. Most of them involve monja, those griddle-splattered, dogs-dinner "pancakes" that are Tokyo's unconvincing answer to the okonomiyaki of western Japan. The one blessed anomaly is Ajisen.
It's not the sole izakaya (dining pub) in the area. But it really is the only one that's worth a special journey to those few square blocks of waterfront landfill. Especially on a chill, damp evening in early spring.
Ajisen stands on a quiet residential street, away from the bright, theme-park ambiance of Tsukishima's main drag. That does not make it a hidden gem. Quite the opposite: For years now it has been vaunted alongside the best of the city's izakaya, rated as highly for its sake cellar as for its excellent seafood.