Argenine,

The version you posted and George Seto linked to is "KIYOSHI KONO YORU" [Silent Night] from SANBIKA [The Hymnal](Nihon Kirisutokyoudan [The United Church of Christ in Japan], 1954, no. 109). The 2nd line should be "Sukui no miko wa" or "Sukui-no miko-wa". The lyrics still have some archaic expressions, though Kirisutokyoudan modified them when they published a new edition (Sanbika 21 [The Hymnal 21], 1997, no. 264) (see underlined words).

KIYOSHI KONO YORU

Kiyoshi kono yoru hoshi-wa hikari,
Sukui-no miko-wa mabune-no naka-ni
Nemuri tamo-o [or tamou], yasurakani.

Kiyoshi kono yoru mitsuge ukeshi
Hitsujikaira-wa miko-no mimae-ni
Nukazukinu, kashikomite.

Kiyoshi kono yoru miko-no emi-ni,
Atarashikiyo-no ashita-no hikari
Kagayakeri, hogarakani.

Some Christmas hymns in Sanbika 21 can be heard HERE (RealAudio and MP3; singer not named). The list is:

No. 231: "Hisashiku machinishi" (Veni, veni, Emmanuel)
No. 245: "Yo-no naranu sakini" (Corde natus ex Parentis)
No. 248: "Essai-no ne yori" (Es ist ein Ros' entsprungen)
No. 255: "Ikerumono subete" (French carol; tune: PICARDY)
No. 258: "Makibito hitsuji-o" (The First Nowell)
No. 264: "Kiyoshi konoyoru" (Stille Nacht)

~Masato