Ocean-bottom pressure gauges of wide and dense ocean-bottom observation networks in Japan, S-net and DONET, observed ocean waves due to the Tonga eruption that occurred at approximately 13:00 JST (UTC + 9) on January 15, 2022. We scrutinized their waveform records to clarify the nature of the arriving ocean waves, and found two significant disturbances between 20:00–21:00 and after 22:00. The first disturbance with a positive-polarity pulse and significant long-period components (1000–3000 s) arrived at S-net and DONET stations between 20:00–21:00 from the southeast, corresponding to the direction of the great circle of Tonga as seen from Japan. This arrival was much earlier than expected for a direct tsunami from the volcano and can be explained by assuming the propagation along the great circle path between Japan and Tonga at a velocity of approximately 300 m/s. After 22:00, significant phases dominated by relatively shorter period components (< 1000 s) arrived from the southeast direction in both observation networks. In DONET, another phase arrived from the south-southeast direction at approximately 23:30 with significant shorter period components (approximately 500 s). Most of the near-trench S-net stations recorded a peak amplitude during the first disturbance, whereas the near-coast S-net stations and DONET stations observed their peak after 22:00. The amplitudes of ocean-bottom pressure change were amplified as the water depth decreases. This amplification behavior differed between the first and second disturbances, and it may have been caused by differences in the dominant period of the arriving ocean waves, as well as differences in their generation mechanisms. This study also found several arrivals of air-wave disturbances that were correlated with the ocean-wave phases, which implies that the multiple disturbances of ocean-bottom pressure were generated by the interactions of several atmospheric pressure waves following the 2022 Tonga eruption with ocean waves.