"Is it just me, or do the Ki-61 and the heinkel 113 look alike?"
No, it's not just you. They look alike. The easy way to tell them apart is that the Ki-61 in that photograph is only a few inches long, whereas the He-100 in the drawing was about 27 feet from nose to tail. The Japanese theorised that their new miniature aeroplanes would be hard to see, but they had to scrap the idea because it was, in all other respects, a silly idea.
The standard online reference for the Ki-61 from which most everything else is copied is this webpage here:
http://www.vectorsite.net/avhien.htmlThe standard online reference for the Heinkel He 100 used to be here, although it has gone down in the last month or so:
http://www.csd.uwo.ca/~pettypi/elevon/baugher_other/he100.htmlIt is still available in Google's cache. Wikipedia's article has lengthy verbatim quotes from this page. Read them both.