Mr. Sakurada have a Shepherd

One rainy day, Sakurada, a college student living alone, picks up a German Shepherd puppy. Suddenly, the puppy turns into a naked boy! The puppy is actually Shima, a dog-shaped alien who has crash-landed on Earth! The puppy is sent to live with Sakurada until his master finds him, and the two get to know each other as they teach each other everything about life on Earth, from how to use the toilet to how to cook...

(Source: Tokyo Mangasha, translated)

Note: Includes two extra chapters.