This looks brilliant. I agree with Kluny's first comment; if someone has an email for @kazuhiroshibuya, please tell him there is currently a spelling and grammatical error on the landing page. Suggest the second sentence be changed from:
"Writebox helps you to concentrate to writing and seamlessly sync your wiring text accross all your devices."
To:
"Writebox helps you concentrate on writing and seamlessly syncs your text writings across all your devices."
