Yuki Hayashi-san used a JRC072D opamp in conjunction with red LEDs for the clipping (most pedals use diodes).
The HEAT BLASTER delivers a truly modern distortion sound, with a tone control plus high-cut and low-cut switches for additional tonal adjustment. The high-cut switch attenuates the presence frequencies in order to produce a mellow tone that retains good projection. With the high-cut switch engaged you can use the tone control to achieve the required degree of projection. This type of setting is ideal for solos. The low-cut switch attenuates the low frequencies, making it easy to attain an ideal blend with bass and drums for a well-balanced band sound. The low-cut switch affects low frequencies that normally cannot be adjusted using amplifier tone controls.