Solo, Omoide Yokocho (Memory Lane) works.
A tight, lantern-lit lane thick with grill smoke and salarymen — cheap yakitori and beer at counters that haven't changed in decades, the most atmospheric quick bite in Shinjuku. The catch: it's tiny and tourist-mobbed at peak, some stalls have seat fees or cash-only counters, and it's more a single photogenic lane than a night out.