BEIJING — Propaganda departments in China and North Korea were in full swing on Wednesday as Kim Jong-un, the North Korean leader, concluded a two-day tour of China that painted the once-reclusive autocrat as a forward-looking leader.

After meeting with President Xi Jinping and briefing him on the summit meeting with President Trump in Singapore last week, the North Korean leader was portrayed in the Chinese state media as eager to learn how to turn a developing nation into a global superpower.

In North Korea, a propaganda machine that for decades turned out anti-American slogans and that denigrated South Koreans struck a new conciliatory tone, publishing posters this week that heralded unity on the Korean Peninsula.

A focus on development

Before his plane took off in the late afternoon, Mr. Kim made “on the spot” inspections of the Chinese Academy of Agricultural Sciences and a subsidiary of the Beijing Infrastructure Investment Company on his second day in the capital.