University president toru was fed up with his son gaku's lack of ambition. hoping marriage would change him, he arranged a meeting with professor oshima's niece, sora but it was toru who had been after her all along. posing as a strict father, he forbade the couple from having sex before marriage. a year later, toru sent gaku on a five-day business trip and put his long-planned training scheme for sora into action.