If Kenneth Branagh doesn’t quite succeed in justifying the conceit of setting his new film version of Shakespeare’s pastoral comedy “As You Like It” in 19th-century Japan — alright, if he completely fails to do so — it probably doesn’t matter that much: Given the vagueness with which Shakespeare treated the question of locale, the forest of Arden could be English, could be French (Ardenne), and therefore could just about be Japanese. Okay, it couldn’t, but it is in this version of “As You Like It,” which airs tonight on HBO.

This marks the fifth time Mr. Branagh has adapted Shakespeare for the screen, following “Henry V,” “Much Ado About Nothing,” “Hamlet,” and “Love’s Labors Lost,” and the Bard could hardly have asked for a more devoted cinematic servant. Away from Shakespeare, Mr. Branagh’s directorial efforts — “Dead Again,” “Peter’s Friends,” “Frankenstein” — have often been overwrought and meretricious. (One still winces at the thought of his role as a stand-in for Woody Allen in the latter’s god-awful “Celebrity.”) But when it comes to Shakespeare, the director has seemed to savor the unenviable task of splashing theatrical poetry onto the big screen, where small stage events can be made to appear very big, and vice versa.

As for this fabled forest, from a visual viewpoint it looks a bit threadbare. Not “bare ruined choirs,” certainly, but somehow insufficiently verdant or lush to cast a transformative bucolic spell over the bard’s collection of deposed courtiers, quarreling brothers, convinced melancholics, and alternately ardent, lusty, playful, confused, and cross-dressing lovers. There’s not much sunshine either, probably because, although the setting is Japan, the film was shot in England. Mr. Branagh’s director of photography, Roger Lanser, tries to mask this with some very pretty close-ups of plants and flowers, but somehow the spell resolutely refuses to be cast.

The director is on much flashier cinematic turf in the opening scene, when Duke Senior is deposed by his brother Duke Frederick (Brian Blessed playing both roles) during the performance of a Kabuki play watched by his “court” — i.e., a collection of English traders and mercenaries hunkered down in one of Japan’s “treaty ports.” With black-clad, Ninja-like creatures sliding down the trees, divers emerging from the water outside the house, and a small army of archers and masked swordsmen doing their best to appear menacing, it all looks a bit overdone, like a campy assassination scene in an Inspector Clouseau movie or a comic book version of “Throne of Blood,” Akira Kurosawa’s terrifying adaptation of “Macbeth” (and T.S. Eliot’s favorite film).

The Japanese setting also allows Mr. Branagh to bring a new twist to the post-coup wrestling match between Orlando (David Oyelowo) and a more experienced grappler brought in by Orlando’s jealous older brother, Oliver (Adrian Lester), in the hope that Orlando will perish. In this case, the wrestling is done sumo-style, and Orlando’s opponent, a real sumo wrestler, is about twice the size he is. Nonetheless, Orlando defeats him and wins the heart of Rosalind (Bryce Dallas Howard), Duke Senior’s daughter. It’s love at first sight, but although Ms. Howard and Mr. Oyelowo are both skilled actors, a certain chemistry is lacking. You believe their words, but not their faces.

Though Duke Senior and other members of the trading post, which is set up in the style of a court, have fled to the nearby forest of Arden, Orlando, Oliver, Rosalind, and her best friend Celia (the daughter of Duke Frederick) have remained — at least for a while. But when Duke Frederick expels Rosalind (whom he kept on only because of her friendship with his daughter) for being a subversive influence, Celia (Romola Garai) insists on going with her. Pretty soon the usurper’s residence is looking as bereft of loyalists as Hitler’s bunker in the last days of World War II. Everyone’s off to Arden!

Having expended most of his gunpowder on the opening samurai-fireworks display, Mr. Branagh now has to settle down and capture Shakespeare’s play on celluloid with a minimum of special effects and the attention, as it should be, given over to the text. Unfortunately, he turns timid and middle-of-the-road, especially when it comes to the genderbending love affair between Rosalind and Orlando. This isn’t just Shakespeare, after all — it’s HBO!

Realizing that Orlando is awfully sweet but a bit of a drip — what with his draping every tree in the forest with a banner bearing her name and his writing corny poems about her — Rosalind cleverly makes use of the fact that she has already disguised herself as a young man named Ganymede while escaping from her uncle to present herself to Orlando as a fellow male (if an unusually pretty one) who can teach him a thing or two about the nature of love and courtship, and by doing so turn him into the lover she wants. Thus “Ganymede” pretends to be Rosalind, Orlando takes Rosalind to be Ganymede, and accepts the latter’s offer to be a stand-in for the former so that he can improve his courtship techniques and win her love.

Unfortunately, decked out in pants, knee-high boots, and a corduroy cap, Ms. Howard looks less boyish than Cameron Diaz, even if it’s a marked change from her appearance at court. Worse, her femininity is rarely obscured long enough for the rush of freedom she gets from adopting a masculine persona to make itself fully felt. instead of relishing the role, and the newfound liberty it brings, she seems to shrink from it, or at least hang back. The result is that all the complex layers of attraction Orlando feels for Rosalind/Ganymede are either lost or unconvincing under the overly literal gaze of the camera. Even if we don’t want Rosalind to look like a young man, we want her to do a better job of imitating one. The necessary comic, parodic swagger just isn’t there.

More successful are some of the minor roles. Alfred Molina, last seen as a CIA chieftain in “The Company,” is wonderful as the foppish Touchstone, who falls for Audrey (Janet McTeer), a country wench. Kevin Kline, as “the melancholy” Jacques, delivers the famous speech about the seven stages of man in an almost offhand way, the camera creeping up slowly toward him as he does so, and does a good job of reminding us that some of the most anthologized lines in Shakespeare are delivered by a character far less appealing than the lines themselves would have you believe. This isn’t just melancholy as self-indulgence, it’s melancholy to make a melancholic blush.

In the end, though, Mr. Branagh’s “As You Like it” founders on a gimmicky decision to set it in Japan — one is reminded of the recent headline in “The Onion,” “unconventional director Sets Shakespeare Play in Time, Place Shakespeare intended” — and a failure to do the Rosalind/Orlando relationship justice. What we’re left with is the magic of the language, which Mr. Branagh knows something about. unless you’re going to adapt Shakespeare very freely, as Kurosawa did, or as Al Pacino did in his superb take on “richard III” (“Looking for Richard”), then you’re generally best off keeping distracting visuals to a minimum and concentrating on the words and the actors’ delivery of them.

When Jacques and Rosalind sit down to discuss Jacques’s melancholy worldview (which Rosalind artfully dismantles), or when Touchstone defeats his rival in a verbal duel, for Audrey’s hand, the film is at its most convincing and enjoyable.

In the end, Shakespeare is what Mr. Branagh has staked his career on, and it remains what he does best. His “As You Like it” may not be quite as I (or you) like it, but it does enough things well to make one hope for more.

bbernhard@nysun.com