Kantai Collection equipment Fairy (Kancolle) representing an American M4 Sherman tank modified by the British to be amphibious. The fairy herself has blonde hair and wears the rounded, olive-green helmet of Allied soldiers in WWII.
The official art contains a historical inaccuracy in that the fairy is shown sitting on top of the flotation screen. In reality, the screens were open on top and were not rigid.
Not to be confused with the M4 Carbine battle rifle, or M4A1 (Girls' Frontline) from Girls' Frontline.