Pirachu is a mouse character that first appears in Hyperdimension Neptunia mk2 as a member of the Arfoire Syndicate of International Crime. Mostly alongside Underling, he does the menial tasks for ASIC, including the distribution of Arfoire chips to people in Gamindustri. In Hyperdimension Neptunia Victory, his alternate self in the Ultradimension is a member of the Seven Sages. He serves as an antagonist and boss in Hyperdimension Neptunia mk2 and Hyperdimension Neptunia Victory.
Devoted to ASIC, Pirachu is committed into furthering ASIC's plans. He would battle those who stand in his way, though he would be quick to retreat if he ever loses. He regards his job in ASIC above all, even swaying off his feelings for Compa just for the sake of staying committed to his job. He develops a crush for Compa after she heals his wounds in their first encounter. Despite seeing Compa as an enemy, he still holds affection towards her.
He has the tendency to say "Chu" when he communicates towards others.
He has the appearance of a dark grey mouse. He has red eyes and two white whiskers on each cheek. The coloring from his shoulder to his hands are black. He has small maroon wings on his back, though he is never seen applying them in any way of flight. On his chest is a red and yellow broken heart design. He he a thin, black tail that has has something similar to a big, black, broken heart in the end. The coloring from his knees to his feet is light red with two stripes on each side. He holds a disc in one of his hands.