His name in Hebrew is: יפת Yepheth (yeh’-feth) Strongs #3315, expansion.
In Jubilees 4:32, it is mentioned that Japheth is the third born son of Noah, but
in Jasher 5:17, it mentions that Japheth was Noah’s first born.
There isn’t much mentioned about Japheth in Scripture and in Jasher, but it mentions
the story when his younger brother, Ham told about seeing his father indecent while
laying drunk on his bed. Japheth and Shem covered their father with Shem’s garment
while walking backwards. (20)
When Noah learned of what his sons had done, he blessed Japheth as well as Shem,
but he cursed Ham’s son, Caanan for the wickedness of Ham.
Ham left his father knowing his son was cursed and he built a city. Japheth learned
of his brother’s action of building the city and naming it after his wife, so Japheth
became envious of his brother, and left his father and built himself a city and named
it after his wife, Adalenses. (21)
Japheth had seven sons, but they are only mentioned in Genesis and Jasher.