No, the US never succeeded in placing or recruiting agents in the Japanese home islands. Japan posed a serious challenge for Allied intelligence services: a closed, repressive society with significant ethnic, linguistic and cultural barriers to successful infiltration.

The US' primary intelligence sources in the Pacific theatre were SIGINT and aerial reconnaissance, rather than HUMINT. The [Magic](https://en.wikipedia.org/wiki/Magic_(cryptography) cryptography programme — a joint effort between Army and Navy signals intelligence units, working in collaboration with the British GC&CS at Bletchley Park — achieved significant success in breaking Japanese codes, both military (crucially, the Imperial Japanese Navy's general-purpose cipher, 'JN-25') and diplomatic (the 'Purple' cipher used by the foreign ministry.) Check out Ronald Lewin's The American Magic for a detailed account of US codebreaking in the Pacific theatre.

US military intelligence and the Office of Strategic Services did recruit a significant number of Nisei (second-generation Japanese-Americans) as operatives, linguists, interrogators and radiomen, but although attempts to infiltrate agents into Japan itself were periodically considered, they were invariably discarded as being too high-risk. Here's an interesting work on the role played by the Nisei in the Army's Military Intelligence Service during the war.

The OSS did mount intelligence-gathering and guerrilla operations behind enemy lines in Japanese-occupied Asia (the China-Burma-India theatre), often in collaboration with local resistance groups — from Chinese nationalist leader Chiang Kai-Shek to Vietnamese communist leader Ho Chi Minh.

In mid-1942, the OSS appointed Captain Carl Eifler to command Detachment 101, a new unit assembled for service in occupied Burma. Detachment 101 proved to be one of the OSS' more successful ventures, and is regarded as one of the ancestors of the modern United States Army Special Forces.

There was one notable American agent in the Japanese-occupied Philippines — but he ended up there entirely by accident. Richard Sakakida was a sergeant in the US Army Counter-Intelligence Corps, stationed in Manila at the outbreak of war. He was captured by the Japanese after the fall of Corregidor, the only Nisei to fall into Japanese hands in the Philippines.

Sakakida was charged with treason by the Japanese military authorities (on the grounds that he had previously held Japanese citizenship), but was acquitted — and subsequently hired by the judge-advocate of the Japanese Fourteenth Army as a translator and servant. He reportedly passed information to the Philippine resistance for several months, and claimed to have posed as a Japanese officer to help the guerrillas spring 500 resistance members from a Japanese prison at Muntinlupa. However, some former resistance members and Philippine researchers have cast doubt on Sakikada's account of his time in captivity, and particularly his claimed role in the Muntinlupa raid. (I'm afraid I haven't read deeply enough into the claims and counter-claims to offer a verdict one way or the other.)