Jinsei wa Barairo ka

Saionji Makoto, heir to the company president, has a secret crush. It's Azuma Kouhei, an outstanding second-year employee who also works as the president's secretary.
Makoto fell for him at first sight… and now, Kouhei’s been assigned as his mentor! Over the moon, Makoto rushes to tell his twin sister, Mami.
But that’s where everything begins...
Because of her strange little spell, Makoto ends up turning into a stuffed toy right in front of Kouhei!?

(Source: Taiyoh Tosho, translated)

Note: Includes three extra chapters.