Chi's Sweet Home(2004)

Chi is a mischievous newborn kitten who, while on a leisurely stroll with her family, finds herself lost. Separated from the warmth and protection of her mother, she feels distraught. Overcome with loneliness, she breaks into tears in a large urban park meadow, when she is suddenly rescued by a young boy named Yohei and his mother. The kitty is then quickly and quietly whisked away into the warm and inviting Yamada family apartment …where pets are strictly not permitted.

(Source: Kodansha USA)

Note: Includes two extra chapters.