I am surprised that until now, no otakus have pointed the inaccuracy in the episode 10 of K-ON.
No, Kyoani. The correct brand is KORG and I am using it.
KORG AW-1 Micro Tuner
Scale: 12-note equal Temprament
Range: A0 (27.5Hz) - C8 (4186 Hz)
Reference Pitch: 410 - 480 Hz
Accuracy: +- 1%
Weight: 10 gram
Recommended instruments: Trumpet, Trombone, Horn, Euphonium, Tube, Clarinet, Saxophone, Oboe, Basson, Flute, Violin, Viola, Cello, Contrabass, Guitar, Mandolin, Shamisen
Advantages: Piezo-based tuner, compact and very accurate
Disadvantages: No backlight LCD, Non standard battery (CR1220)
The disadvantages are corrected in the new released KORG AW-2