In the original (Touhou) story, Remilia and Flan are not human and they have very long life. So I thought of making stories where predator types live many times longer than the normal types. If they try hard, they might be able to live for 30 years or soI'm really scared thinking if Lily of the Valley is really that poisonous from seeing that murder scene in Breaking Bad.
At first, I planned on using Wolf's Bane. But then I thought that the Lily looks like yukkuri's stalk pregnancy so they would probably like it... and changed my plan.