102K Nintendo Switches were also sold in Japan in this period. Switch installbase in Japan is now 1,205,087.
The first Splatoon’s Japanese debut sales were 156,610 (physical) on a Wii U install base of 2,333,622. Splatoon 1 then went on to sell 1,512,789 units (according to Famitsu) not counting eShop sales.
Update, Media Create's numbers:
Media Create report that Splatoon 2 sold 648,085 units and 98,999 Switches were sold (in the same time period).