Since the release of 2004's Walking Cloud and Deep Red Sky, Flag Fluttered and the Sun Shined, Japan's Mono have hollowed their own cave in the mountain of post-rock.

They've incorporated everything from live electronics to orchestral strings and choirs while their harmonic, textural, and timbral palettes have become increasingly more melodic and thematic.

On the two simultaneously released albums The Last Dawn and Rays of Darkness, Mono offer starkly contrasting aspects of their musical identity.

The Last Dawn is the more familiar-sounding of the pair.

As its title suggests, this is an ending, a summation; in executing it as such, the band pursues a much simpler melodic context than on 2013's For My Parents.

The slow-building tension and release over the set's six tracks portray the quality of light -- brilliant, golden, soft, warm -- but also contain its oncoming nadir.

"The Land Between Tides" -- the set's intro and longest cut -- displays a recognizable architecture, with wind-washed ambience, an underscoring repetitive, fingerpicked guitar pattern, and an emergent bluesy solo guitar statement that gives way to layered cellos, violins, drums, and increasingly more aggressive strumming and feedback.

A single soaring guitar line ratchets up the intensity (and anxiety) -- illuminated by thunderous drums -- until it has nowhere to go but back to a point of origin.

That's on "Glory," where a piano leads strings and guitars into silence.

"Kanata" commences with piano and guitar patterns in a chamber-like interplay before transforming into a swirling shoegaze blur.

"Cyclone" is nearly processional, an instrumental rocker set in waltz time; its twinned guitars, bass, drums, and glockenspiel create a washed-out void.

"Elysian Castles," easily the most lyric thing here, showcases piano, strings, tom-toms, and kick drums, as guitars provide adornment with near pastoral poignancy.

While the lyricism at the start of "Where We Begin" is so gentle as to almost become transparent, it eventually builds to the most emotionally transcendent expression on the album as whirring, exultant guitars revel in a shattering expression of ecstasy.

The closing title track asserts itself only briefly.

At the moment of full articulation, it gets scaled back to a melodic essence and fades away.

The Last Dawn is intensely emotional music: uncertainty, tenderness, love, joy, anxiety, and loss all play a part in its unfolding.

Musically, it encapsulates everything about Mono's last decade carefully, holistically.

While it stands alone and can be enjoyed separately, it also serves as an entry point for the blasted, bleak roar that is its companion, Rays of Darkness.

When paired, they become an opus.