According to this MCV piece, PSP sold 270,750 units in Japan in May.
The handheld took 37.3 percent of all console sales last month.
It was followed by Wii at 220,052 units (30.3 percent) and DS Lite in third, which sold 163,930 (22.6 percent).
Fourth was PS3, which sold 34,674 units (4.8 percent). PS2 sold 29,569 units (4.1 per cent), whilst Xbox 360 brought up with rear with 6,883 units (0.9 per cent).