The crude Nakajima Ki-115 Tsurugi was a candidate Kamikaze aircraft with 104 built by war's end, but none of them were used operationally, to my knowledge.
There were quite a few versions of the Mitsubishi G4M, prototype G4M1, then production G4M Model 11, then Model 12 with different engines, then G4M2 Model 22 with laminar flow wings, other changes-different engines again, a Model 22A, a Model 22B, Model 22C, a G4M2a Model 24, a G4M2a Model 24A. Model 24B, Model 24C.
Then experimental variants: a single G4M2b Model 25, two G4M2c Model 26 with turbochargers, and one G4M2d Model 27.
As stated, the designators for Ohka-carrier G4Ms are above.
The final attempt to improve the G4M for combat came with the three prototype G4M3 Model 34s; first being completed in January 1944 with again revised wings. Variants of the G4M3 model 34 included an ASW/transport G4M3a Model 34a not built, and two experimental G4M3 Model 36 aircraft with the turbochargers of the G4M2c Model 26. Whew!!
A heavily armed Navy fighter derived from the basic G4M was designated G6M1 with just 30 built. These were converted to G6M1-K trainers and G6M1-L2 transports. Counting prototypes the total Mitsubishi production of the G4Ms was 2,416, plus the 30 similar G6Ms.
Noted victories-G4M1s sank the battleship HMS Prince of Wales and the battle-cruiser HMS Repulse just three days after the 7 December 1941 Pearl Harbor attack and took part in the first raid of Darwin, Australia. There is more, but finally two G4M1s carried the Japanese surrender delegation to Ie Shima enroute to discuss the final requirements of Japan's unconditional surrender, ending on VJ day.
This has gotten away a bit from the Ohka, but the Mitsubishi G4M was quite a Japanese Navy aircraft in its many versions, spanning 1937 to 1945.