The Ki-61 is IMO the third best looking single-engined DB-powered fighter of the war. The other two are the Fiat G.55 (with notable mention to the Re.2005 and Macchi C.205V) and the Heinkel He 100. The Bf-109 just never tried to be streamlined, instead is covered in bulges and intakes.
The G.55 reminds me of the Finnish VL Pyörremyrsky, its northern sibling, which of course never passed the prototype stage during the war. As far as I can see, the two planes had a very similar performance, as well.