The Japanese disliked it intensely.
What's your source for this?
The three He 100D-0 preproduction aircraft were sold to Japan and were delivered there in May 1940. The Japanese were quite taken with the plane and did intent to manufacture it, but Heinkel failed to deliver the necessary jigs. According to Francillon, René J. (Dr.), Japanese Aircraft of the Pacific War (Annapolis: Naval Institute Press, 1995. ISBN: 0-87021-313-X), pp.112-20
Some will claim that The He-100 was the inspiration behind the Ki-61 (others the 109) but the only engine (DB 601A) was 'copied' (Kawasaki Ha-40). There's no doubt that the looks of the Ki-61 resemble the He-100 and 109 (at least enough to keep some folks speculating).
Also, the He-112 was what was competing against the 109, and the 109 won that competition. With that failure Heinkel went back to the drawing board and came up with the He-100. The initial He-100 proto-type had issues as well. By this time the 109 was already a proven design. Six prototypes were eventually sold to the Soviet Union and three went to Japan (D-0s). 12 D-1s were flown by Heinkel pilots to defend the Heinkel factories.
Along the way the He-100 did break some speed records but the radiator design proved problematic and the He-100 was redesigned with a more tradition radiator which increased drag and decreased top speed.
It would be a pointless adition to AH. Even the He-112, which saw limited service among various airforces, would be useless except if and when they decide to model planes of the Spanish Civil War.
EDIT:
He-100D-0s were armed with 2 x MG17 and 1 2cm MGFF.