The Ireland team enjoyed some gym and pool time in Tokyo yesterday before a walk through session in the afternoon.
Marmion scored an outstanding try in New York last weekend and is keen to build on that 55-19 win over the USA.
Connacht's Tiernan O'Halloran, Quinn Roux, Dave Heffernan, Finlay Bealham and John Cooney are also in the Ireland squad for the summer tour.
O'Halloran and Roux started the USA clash alongside Marmion as Heffernan made his international debut off the bench.
The team for Saturday's first Test against Japan will be named tomorrow with the game kicking off at 6am.
Saturday 17th June
Japan v Ireland, Ecopa Stadium, Shizuoka, 6am Irish time;
Saturday 24th June
Japan v Ireland, Ajinomoto Stadium, Tokyo, 6.40am Irish time;