For long-haul Nyquist-wavelength division multiplexing superchannel transmission, an inter-subcarrier nonlinear and linear interference canceler (INIC) is proposed. This approach consists in detecting the adjacent subcarriers, regenerating them thanks to the Volterra series model of optical fiber, and removing them from the subcarrier of interest. Different ways to implement the INIC are described and compared with the well-known techniques, such as digital backpropagation (DBP) and Volterra-based nonlinear equalizer (VNLE) implemented in a subcarrierwise manner. Significant performance gain (on either the Q factor or transmission distance) is observed. In the context of 400 Gbps scheme, the transmission distance gain is up to 500 km compared with the DBP and VNLE.