
The world No 25 quickly conceded the first set 6-2, before putting up a fight in the second set to push the match to a 6-6 tiebreaker that world No 56 Nishioka eventually won.
The match lasted one hour and 49 minutes.
This is the fifth time that the two players have faced each other, Nishioka having won all five previous times.
British No 2 Evans entered the Korea Open after making it to the semifinals in San Diego last week, but failed to repeat that success in Seoul.
Nishioka is currently world No 56 and reached a career-high of No 48 in February 2020. He became the top Japanese player in June of 2021 and still holds that spot.
Nishioka will face either Taro Daniel or Emilio Gomez in the round of 16.