PRIME is Japanese PRedictive Input Method Editor.

PRIME predicts user's input words using the knowledge of natural language and
the history of user's operations, and reduces the cost of typing by the user.
For example, if a user wants to input "application" and types "ap" as the
beginning characters of the word, PRIME might predict some candidate words like
"apple", "application", "appointment", etc...  And then the user can input
"application" easily by selecting the word from the candidate words by PRIME.