Lieutenant Japar was a Klingon officer in the Klingon Defense Force who served as an engineer aboard a Bird-of-Prey.
Following the Klingon Empire's withdraw from Cardassian space, Japar's Bird-of-Prey returned to Deep Space 9 where it underwent repairs. While at the station, Japar was taken to the infirmary with plasma burns. According to "Julian Bashir", his wounds looked worse than they were.
Miles O'Brien was trying to track down Japar because he was unable to "make head nor tail" of the power relay systems on Japar's Bird-of-Prey, but he had just missed the lieutenant by the time he arrived at the infirmary. (DS9: "By Inferno's Light")
This character was only mentioned in dialogue.
According to the Star Trek Encyclopedia, 4th ed., vol. 1, p. 129, this Klingon's name was spelled as Ch'Par.
This character wasn't mentioned in the script. The "Japar" spelling comes from the episode's subtitles.