Kawasaki Ki-61 "Hien" (Tony) pt. 2 - video

Here's the second part of the video and for those interested, additional intriguing information about the "Hien" from the Japanese Wiki:

Nickname/Designation

The prototype designation, the Ki number, was Ki-61. The official designation, Type 3 Fighter, derives from its official adoption in the 2603rd year of the Imperial calendar (1943 (Showa 18)). According to Watanabe (2006, p. 153), the official adoption was in June 1943 (Showa 18), while according to Komine (2007, p. 143), it was October 9, 1943. Although mass production actually began in 1942, the "Type 2" designation was delayed until 1943 to avoid confusion, as there were already the "Type 2 Single-Seat Fighter" (Shoki) and the "Type 2 Twin-Seat Fighter" (Toryu).

Its nickname was "Hien" (Swallow), and unit names and abbreviations included Type 3 Fighter, Rokuichi, Ki no Rokuichi, and Rokuichi Fighter. Within Kawasaki, it was called "Rokuichi", but after the introduction of the Type 2, it came to be called "Ichigata" or "Nigata".

Some sources state that the nickname "Hien" was announced in the latter half of 1944, but it was actually announced in an article in the Asahi Shimbun dated January 16, 1945, reporting on the activities of the 244 Sentai, which was engaged in the air defense of mainland Japan. The article states that "its nimble agility resembled that of a swallow soaring through the blue sky, hence the name 'Hien' (Swallow)." Mitsui (1989, p. 20) explains that it derives from its distinctive style, characterized by its long, slender wings with a high aspect ratio. According to Ikari (2006, p. 127), the nickname appears in Kawasaki Aircraft's timeline as of January 1945.