I draw up this tab if anyone is interested. Its actually for sanshin, but its an easy piece and fun to play whilst singing.
https://drive.google.com/open?id=0B0TPTkCK1oYGZkl6eXFGUTB0TTQ
Lovely song, I like the title to begin with. Thanks for sharing. 
I LOVE this song. Thank you!
not sure i understand all the notation…
This matches up very much with sheet music I use to play this. Great song.
Oh, I forgot about this. I rewrote the tab more correctly, including the pitch shift. Will upload the better version tonight.
Umi no koe, maybe is the song by the band Begin, but excuse me for my ignorance… it also can be a traditional Okinawan minyo, like warabi gami, done and redone by famous artists known in mainstream Japanese music