46-:ri9

46-:ri9 (called on the JASRAC database) is Disc 3, Track 11 on the XenobladeX Original Soundtrack. It is split into two parts: the first plays from the start until 2:27, and the second plays from then until the end.

The first part plays in Sylvalum during the day. The second part is a brighter remix of the first and plays in Sylvalum at night.

The brighter part of the track being used as the music during the night makes Sylvalum the only area in the game (or, for that matter, the Xenoblade series as a whole) whose day theme is significantly more subdued than its night theme.

Etymology
4 is read in Japanese as 'shi', 6 as 'ro', '-' (potentially) as 'no', ':' (potentially) as 'tai', and 9 as 'ku'. Together (along with the 'ri') they make 'Shiro no Tairiku' ('the white continent'), which is the Japanese name for Sylvalum. This also aligns with the JASRAC version of the title.