OpenAI job listings show six ad formats in development: text, image, video, native, conversational, and interactive (DIGIDAY Japan, July 9, 2026). Three ad-format engineering roles cover infrastructure, iOS, and Android. The company spent its first four months building the ad business foundation. For foreign brands in Japan, ChatGPT is becoming a paid channel with formats beyond search-style text. Budget owners should reserve test spend before Japanese inventory opens. Early advertisers set the benchmarks.