Song Identification : Movie 1: The Time Bombed Skyscraper

[The Contractor]

Hi guys,a newbie here..so I just resumed watching DC after a veryyyyyy long time and I started off with the first DC ever produced movie, The Time Bombed Skyscraper and I fell in love with one particular song played in one of the ending scene ( Its not Happy Birthday tho)

In this scene, Conan and Ran were separated by a pile of rubble after the initial detonation of the bomb.Conan guided Ran on how to defuse the remaining bomb till the very last moment,in which two wires( Red and Blue) which were not in the schematics were present.Knowing that they will die, Ran said happy birthday to Conan (Shinichi) and this particular song that I am looking for was played.Anybody have any idea what song was it?