The Royal Tutor Vol. 17 (manga)

Thanks to Heine's teachings, the four princes have overcome a lot and matured into leaders in their own right—so the time has come for King Viktor to officially choose the heir to the throne. But in order to do so, he gives his sons one last task: to give a speech in front of the entire kingdom. Having never given one before, the four younger princelings are at a severe disadvantage...but luckily, they’ve got Heine to whip them into shape! The royal comedy about princes and their tutor comes to a majestic end in this final volume!