The background on this CM is kind of thick. It is an affectionate satire on the human drama surrounding the construction of the Seikan Tunnel, connecting the Northern island of Hokkaido with the main island, Honshu.
The story of the tunnel construction was immortalized in an episode of the NHK documentary “Project X: Challengers.” The background music in the CM, a folk-rock song by Miyuki Nakajima called “Earthly Stars (Unsung Heroes)” (Chijo no Hoshi), is well known as theme music for the documentary. The song is connected in the popular imagination with the tunnel construction, with the stoic, manly virtues that drive human achievement in general, and with the numberless, nameless heroes who built modern Japan. But it can also be used as stock music for parodying this kind of popular folklore, as it is here in the TLJ CM.
The song is something of an international hit and is notable for its macho, heroic vibe, powered especially by Nakajima’s quavering contralto and the use of big drums. Official video:
Lyrics and translation here by J-Pop Asia.