Japan's small 'snack' bars may be a mystery to most, but to their loyal and mainly male customers they are cozy havens where they can unwind with friends and share life's ups and downs with a mama-san who's always there for them

The glitter along the walkways of nighttime Japan in every color of the rainbow: signboards inviting passersby into places with names like Dream, Love or Reverie that suggest romance might be just a step away.

Having long wondered just what may be on offer, you finally pluck up courage to go inside. Hauling on the heavy, brass-trimmed door, instinct at once confirms this is no house of ill-repute, as you spy several men and a neatly dressed, middle-aged woman dropping ice into a glass of whiskey for a gentleman lounging on a sofa beside her. An enka ballad's tinny strings and saxophone ooze from a karaoke machine.

Like an explorer, you have stumbled across a peculiarly Japanese social grouping: the watering hole known as a sunakku (snack), and the nighttime tribe that gathers there by night. Your discovery has come just in time.

Though still ubiquitous features of the social landscape, snacks remain something of a mystery to all but the graying salarymen who are their chief patrons. Having first sprung up in the mid-1960s, before peaking at around 250,000 in the early 1990s, today snacks are becoming passe, with younger drinkers and increasingly cash-strapped salarymen heading for cheaper stand-up bars to unwind after work.

A snack resembles a bar, but has a homier feel to it. In a system called botoru kiipu (bottle keep), regulars are poured drinks from bottles labeled with their names and lined up behind the bar -- while they nibble on side dishes of traditional Japanese food. (Hence the name.) The price of a visit starts at around 3,000 yen at the low end of the scale but can easily jump to five times that.

Don't bother asking for a pina colada or some hoity-toity Merlot. Chances are that whiskey, cognac, bourbon, Japanese shochu and beer are all you'll find on offer. But then booze isn't the primary attraction of a snack. That honor belongs to the proprietress herself, the snack's mama-san, known to her regulars simply as "mama."

More than physical comeliness, it is the mama's warmth and sensitivity that lure customers through the doors -- an ability to flatter, humor, scold and salve a whole roomful of male egos.

Sure, mamas flirt. But the most professional among them know that it is wise to keep such behavior within the confines of the shop. For Mama is not a girlfriend, but a source of platonic consolation, a shoulder to cry on (sometimes literally) or a counselor whose nuggets of womanly wisdom can, say, help a man on the verge of harpooning his marriage to rescue it instead. (It is no wonder some say a Japanese man has three mamas: his biological mom, the mother of his children . . . and the mama-san at his snack.)

However, penetrating the culture of a snack is harder than it may seem. Non-Japanese-speaking foreigners are often turned away by a mama-san unable to explain the bottle-keep system. Even many Japanese get the butterflies when peering into an unfamiliar snack.

So to lift the veil on this somewhat mysterious corner of Japanese culture, this writer and photographer Natsuko Utsumi recently became brief regulars at two typical snacks in Yokohama in an effort to pinpoint what it is that makes these places such an integral part of many people's lives.