The possibility of igniting D3He plasma in the fast-ignition, inertial confinement fusion scheme is discussed. Use of a small amount of DT fuel as an igniter is indispensable in order to mitigate the requirement on driver energy. Simulations have been made for a DT/D3He fuel compressed to 2000 ~ 4000 times the liquid density. The DT igniter is placed at the edge of the compressed fuel. The work shows that it is possible to obtain sufficient pellet gains (100) with realistic driver energy below 10 MJ. The essential roles of DT fusion neutron and nuclear elastic scattering are clarified. The possibility to reduce the amount of DT fuel is discussed.