The IFX-V400 Gawain II is a knightmare frame used by the Holy Britannian Empire, specifically the Knights of the Round, by the Knight of Two Henry Tauren in Code Geass R2: Twin Demons . However, later in the story the pilot joins the Novus Empire of Briton and alligns himself with Luis vi Britannia.
This knightmare frame is based upon the original IFX-V301 Gawain. It is also based upon the RPI-V4L Gareth. The difference between itself and these two frames is that the Gawain II is white and gold. It also has missile launchers from the Gareth on its legs and upperbody. Another difference is the float system. It has 4 wings, put into an x shape and it also has the float system of the Gareth for emergencies.
This knightmare frame made its appearance in Chapter 17 of Code Geass R2: Twin Demons. It is piloted by Henry Tauren, the Knight of Two and it battles with Li Xingke and the Shen Hu. Later on, the Gawain II heads to the Tokyo Settlement to battle Nex.
By Chapter 23, it has become a part of the N.E.B.'s arsenal and is involved heavily in the fight for Japan.