Stuart Hogg became Scotland's record Test try scorer as he led his side to a scrappy 29-20 victory over brave Japan.
Andrew Conway notched a hat-trick and Johnny Sexton stylishly celebrated his 100th cap with a try as Ireland secured a 60-5 win over Japan.
Scotland head coach Bryan Easson has named four uncapped players in his 26-player squad to face Japan on November 14.
Ireland will host autumn internationals against Japan, New Zealand and Argentina, the Irish Rugby Football Union has announced.
Recap Saturday's Test rugby outside of the Lions as Ireland, Wales and New Zealand registered wins over Japan, Canada and Tonga.
The Lions eased to a 28-10 victory over Japan at Murrayfield, but it was not all good news for Warren Gatland as captain Alun Wyn Jones left the field injured.
The Lions face Japan at Murrayfield shorn of key players, against a side who have not played for 20 months, and in a match uncertain of Test status.
Michael Leitch will captain Japan vs the British and Irish Lions, while Clermont's Kotaro Matsushima and ex-Bath back-row Amanaki Mafi start.
The British and Irish Lions have suffered a setback ahead of Saturday's pre-tour clash with Japan after Hamish Watson was ruled out by concussion.
Alun Wyn Jones will lead the British & Irish Lions in their warm-up Test against Japan on Saturday, with Dan Biggar and Conor Murray partnering at half-back.
England's Eddie Jones has defended his April trip to Suntory Sungoliath in Japan, insisting coaches need to practice in the off-season.
Japan will face the British and Irish Lions in Edinburgh next month with a squad including 19 players who helped them to the quarter-finals of the 2019 Rugby World Cup.
England have been drawn alongside Japan and Argentina for the Rugby World Cup 2023, while Ireland and Scotland will face defending champions South Africa.
Gregor Townsend says "reality" is setting in with Scotland's draw for the Rugby World Cup 2023, while Ian Foster says it will be "special" to play hosts France.
The draw for the 2023 Rugby World Cup takes place on Monday, a little over 13 months after the Springboks lifted the trophy in Tokyo.
The British and Irish Lions will play Japan for the first time in a one-off Test match at Murrayfield on Saturday June 26.
Rupert Cox is joined by Michael Leitch and Blaine Scully to discuss the state of play in Japan and the United States.
The 2020 Six Nations campaigns will conclude on the weekends of October 24 and 31, World Rugby has announced.
Fiji and Japan are set to join the Six Nations teams for a festival of rugby, which will replace this year's autumn internationals.
World Cup champions South Africa and Japan could feature in an international ‘festival of rugby’ tournament alongside the Six Nations sides this autumn.