The episode begins with Prince Ten'yuu repeatedly visiting the Research Institute for Medicinal Plants and asking for Sei each time. Sei's colleague Jude is visibly stressed, as he constantly has to fend off the prince's inquiries. Sei and Jude agree that they must be cautious around the prince, as he seems inexplicably fixated on Sei.

When Sei and Prince Ten'yuu finally meet at the institute, they engage in a lengthy conversation about potion-making and medicinal herbs. Sei skillfully avoids revealing her unique ability to produce high-quality potions, which leaves Prince Ten'yuu curious but not overly suspicious.

Seeking advice, Sei turns to her friend Liz and Commander Hawke. She learns that Prince Ten'yuu, supported by Captain Ceyran, is likely searching for a skilled alchemist, regardless of his interest in the Saint. Intrigued and somewhat relieved, Sei decides that she must understand the prince's true intentions.

To get closer to the truth, Sei and Commander Hawke stage a conversation about the complexity of brewing high-quality potions for certain illnesses. Prince Ten'yuu eavesdrops and later confronts Sei. Eventually, he reveals his motives: he is desperately searching for a cure for his mother's illness, which has left her unable to use her arms and legs. This revelation explains his keen interest in high-quality potions.