In the case of Japanese, there is 午前・午後 for 12-hour time. e.g. 午後９時に着く (arrive at 9 P.M.). If it's obvious from context, then only the hour is said. e.g. in「明日３時にね」, the flow of the conversation disambiguates the hour (it's also unlikely the speaker means 3 A.M.)
There are also other ways to convey 12-hour time. e.g. 朝６時に起きる (wake up at 6 A.M. / wake up at 6 in the morning).