Hidden inside an unassuming 1939 walk-up, Zigu Japanese restaurant and sake bar charms with a lively setting and simple yet remarkable dishes. String lights and bistro seating beckon guests to its courtyard terrace. But it’s the inside that seduces me: Large, colorful liquor bottles parked on the bar. Sake boxes stacked high. Bartenders and chefs abuzz in the joint bar and kitchen. And is that “Jailhouse” by Sublime I hear?