Forest is the father of Laura Haruna, the human girl who owns the main character Hamtaro. He works at an office and is married to Marian Haruna, Laura's mother. As a character, Forest is known for his anxious and somewhat dramatic nature, particularly when it comes to his daughter. He worries easily about Laura and has a tendency to overreact if she is out for a long time or if he feels she might be in any kind of trouble.

His role in the story is primarily as a supporting human adult in Laura's life. He is a caring parent who is very proud of his daughter, often calling her affectionate nicknames like pumpkin and cheering her on in her endeavors. This pride extends to a friendly but competitive relationship with his next-door neighbor, Conrad Iwata. Forest and Conrad are good friends, but they frequently compete with each other over frivolous matters, including, notably, a rivalry concerning their respective daughters. This competitive dynamic is a recurring source of lighthearted conflict and humor in episodes that feature the human families.

Forest works late at the office often due to the amount of work he has, which is a characteristic that explains some of his absences from home during the daytime. Another notable trait is his distinct weakness for chocolate. In the original Japanese version of the anime, Forest is shown to get drunk and forget things, a trope common for a salaryman character; this specific behavior was generally removed for the English-language dub. His personality and reactions provide a gentle, parental counterpoint to the adventures of the young human characters and, by extension, the Ham-Hams.