For the culinary-minded traveler, any visit to Tokyo should include a dinner of unagi — tender, unctuous grilled freshwater eel. There are genteel eel specialists, like the memorable Yama-no Chaya, which opened in the early 20th century on the leafy grounds of Hie-Jinja Shrine. By contrast, there’s Unagi Kabuto, at 35 a relative newcomer: a friendly, charcoal-smoke-scented storefront in Tokyo’s Ikebukuro neighborhood, whose lively streets are peopled more by touts in skinny suits than by elegant women in kimonos.