I have not heard of any Japanese who fled from their homeland; but its interesting to see the different Japanese collaborates who tried/or did flee to Japan. To name three, the Emperor Pu Yi of Manchukuo (the Japanese puppet state in Manchuria), try to flee before the Russians arrived at his palace, but was caught, and put under house arrest in Russian Siberia, before he was transferred to the Tokyo War Crimes Tribunal, and then to the Communists in China.

Subhas Chandra Bose, who was the leader of "Azad Hind", a group seeking to liberate "India" from the British through military force (after the Indian National Congress refused to use armed force against the British), had to flee on a plane, from Burma to Japan. But his plane crashed over Taiwan before he could reach there.

And many of the followers of Wang Jing Wei, who was the leader of the Beijing-Nanjing Chinese government in China, some of whom tried to flee to Japan in 1945, but all of whom were tried and executed. Wang Jing Wei himself died in 1944, before the end of the war.

In the end Japan offered no safe haven for any criminals* who sought safe haven there. Many collaborates however just switched their tune away from "pan-Asianism" and focused more on native nationalist movements, whether they be Sukarno and Hatta of Indonesia or Aung San of Burma. Phibun (he has a longer Thai name) of Thailand (a sort of Horthy, if you know your Hungarian history), was put on trial at the behest of the US, but as he was still a popular figure, he was released, and continued to be a power-player within Thai politics. Much like Miklos Horthy in Hungary, he remains a controversial figure in Thai history.

*Criminals being defined as persons who were wanted by specific war tribunal courts, either in Tokyo or outside.

Sources: If you want further information on a specific individual let me know. But this is all very general history, that any proper book on the Pacific War should discuss.

Several Japanese for a time escaped to foreign lands by enlisting under foreign service. One of the most notorious was Colonel Masanobu Tsuji, who contributed to some of the worst war crime incidents, such as the Bataan Death March, the Sook Ching massacre in Singapore, and a notorious incident where he executed a captured American pilot and ate his liver. He escaped by exploiting contacts he had in China and worked for Chinese intelligence for a time after the war. Later, he returned to Japan, before disappearing in Laos during the Laotian Civil War.

A few other Japanese assisted the Chinese to a varying extent. Nemoto Hiroshi, an officer in charge of overseeing the evacuation of Japanese civilians from Manchuria to China, and later the repatriation back to Japan, later joined Chiang Kai-Shek's forces in Taiwan and Quemoy, where he assisted in the Battle of Guningtou on Quemoy and helped the Kuomintang repulse the Communists, shortly before being allowed to secretly return to Japan in 1952.