- "The rain sure nice, isn't it? it brings back old memories."
– Gole's opinion about the rainy weather.
The episode is followed up by The Mush Sisters are Shy.
On a rainy day, Sumire finds a mysterious letter in the library. So she subtly suggest to her Fairilu friends that they go out into the rain to find about this letter.
Out in the rain, Nozomu tries to meet a Fairilu by opening a Fairilu Door in various ways, but is unable to. He thinks Fairilus may not like the rain and decides to try again later. The rain stops shortly and Nozomu ganders upon a rainbow in the sky.
In the cafeteria, Lip and Himawari recently finish their homework with Omatsu. Relaxing, Himawari becomes dismayed that she can't play outside due to the rain. Then she sees Fairilus Sun and Amemi; she comes up to Sun and requests him to use his Fairilu Magic to stop the rain. He casually declines, but Himawari begs him. The two decide to cheer Himawari up by using their sequential magic to make Amemi's rain clouds appear then cleared away by Sun's sun. The two explained that they needed the rain and that even the two can't change the weather.
Later, Sumire comes up to Lip and Himawari and tells them they like to go for a walk in the rain. But two says they will get wet doing so. So, Sumire uses her magic to give the three of them rain gear. Prepared for the rain, the three go outside and have fun walking around in the rain.
The three continue walking and Lip wonder much longer are they going to walk. Himawari starts to become bored, in the process she frequently gets buffeted by the harsh windy weather. Eventually, Himawari becomes angry and wants to go home. At loss for words, Sumire feels guilty for letting her down; the two end up in tears.
Lip starts to feel bad for them and wondered what to do now. Then her key begins to glow. Getting an idea, Lip casts a magic spell to make the rain fun. The result was a sound of music resonating from the rain and Lip begins to have fun. Himawari and Sumire eventually regained their happiness and start dancing along with Lip.
After which, the rain stops and the sun appears. The three continue their journey and they come across a visual display of a series of rainbows in the sky, in which Sumire calls it the "rainbow bridge". She explained that it appears every time the rain stops and that the place they are at is the only place in Little Fairilu they can see the rainbow bridge. She wanted to share this with the two, but was unreasonable in the process and feels sorry for doubting them. Seeing how Sumire really wanted this for her friends, Himawari burst into tears and feels very sorry for doubting her. The two accept their apologies.
Lip asked how did Sumire knew about the rainbow bridge. She explained that she found an old letter in one of the books in the library. The letter itself appears to be an unsigned love letter about the rainbow bridge. Lip imagines that the writer saw the rainbow with the person they truly loved, just like the three saw together. Lip and Himawari thank Sumire for sharing the great experience together as friends.
Meanwhile, Marje was observing them and becomes surprised to see that Sumire has the letter revealed to have belonged to her, leaving her very embarrassed. Gole, also aware of the letter and the three's adventure, playfully comments the 'memories' they've shared together in the rain just like the three did. Flustered, she takes some books and changes the subject to prepare for lesson plans and leaves, only to be unaware that another letter falls from her books. Lip, Himawari, and Sumire head out; Himawari comments she begun to like the rain now and Lip suggest that they should go see the rainbow bridge again when it rains again.