A single crack in a brick wall in Tianjin has become a social media sensation, thanks to local art teacher Yuan Yuan, 32, who turned the flaw into a charming mural of Nick and Judy from the film Zootopia.

The work is the latest of Yuan's many street repair projects. Since last autumn, she has spent her spare time transforming cracks, peeling walls, and tree holes around schools into playful art.

"I initially wanted to encourage kids," said Yuan, a teacher with 12 years of experience. Her paintings often use homophonic puns; a flying rabbit represents "making rapid progress", while a mouse holding a "you're the best" sign plays on a Chinese idiom.

Due to her use of durable acrylic paints, her works are ephemeral, lasting about a year.

Yuan leads a small team from her art institution in this public welfare effort.

"These little paintings are like seeds," she said. "I don't expect a forest; just scattered bits of green are enough."

Hu Yang and Xu Xinran contributed to this story.