Buddhist monk Kukai was born in Kagawa and is (falsely) believed to have invented Hiragana, one of the three major Japanese writing systems.
(Hiragana evolved from kanji, so it is incorrect to say someone invented it)
There is a Game Boy themed post office box somewhere in Kagawa. For the sake of the privacy of the residents, its exact location is kept secret. DO NOT RUIN THIS FOR THE REST OF US. Allegedly it is in the mountains of Sanuki City.