Stevenson and the Kubota Spears currently sit second on the Japan Rugby League One table, and will travel to the Mie Honda Heat on Sunday, January 11, for their round four matchup.
Plummer has been in fine form for Clermont in the Top 14 so far this season, after leaving the Blues after their Super Rugby Pacific semi-final defeat in 2025.
The Cherry and Whites threatened a late comeback with tries from Mikey Austin and Ciaran Knight but Newcastle held on to clinch their first Prem win from nine outings.
Ulster produced a strong second-half performance to sweep aside Munster 28-3 in a one-sided victory that lifts them up to second in the United Rugby Championship.
Leinster have welcomed back Will Connors for the first time since October while leaving overseas signing Rieko Ioane out of the matchday 23 for Friday’s BKT United Rugby Championship meeting with Connacht at Aviva Stadium.