Kojiro

Prunus Mume
Japanese Apricot
Ume

Kojiro
古城（こじろ）
'Kojiro' is typically grown for fruit,  but will produce enjoyable flowers, and can also be used for bonsai.  Its fruit are darker blue, with thick flesh that is relatively hard.  It is known for its early harvest time.

Primary uses
Ume juice and umeshu.  

Pollination
It will benefit from the presence of another variety.