When Yumiko was a child, she was given a puppy by a neighborhood boy, Toshi-chan. She named the puppy Aniline, and always kept it with her, even after Toshi-chan moved away. She thought fondly of Toshi-chan, and called him her first boyfriend, long after he'd left.

Time passes, and Yumiko and Aniline go to school one day... and Yumiko is sure that the new boy at school, Hamao, is the same Toshi-chan from childhood. But he doesn't seem to want to remember her or her Aniline, and rebuffs her coldly.

However, when Aniline is in trouble, he warms up to Yumiko and tries to help out. And by the end of the story, it's evident that the three of them are happiest being friends - Toshi, Yumiko, and the dog - always together.

I tried not to give away the ending, but I had to be very vague. However, the story is sweet and poignant, and I definitely recommend it.

If you want to read the story in its entirety, I suggest the excellent translation at Alex Glover's The Manga of Takeuchi Naoko. You can find this story in the "Miss Rain" section.