Luna Yukari is a lonely individual. Believing no one can understand her, she creates her own complex AI that she names "Carbuncle".
Carbuncle
Carbuncle is a semi-sentient AI that Luna Yukari programmed to be her best friend. Carbuncle cooks, cleans, and accompanies her during day-to-day activities. Carbuncle is however capable of learning how to adapt to her surroundings. Many of her sub-programs are accessible via Luna's Duel Disk. The password to access Carbuncle's files is "Crystal".