As the name suggests, Koga's popular series ``Hooyoroi Hai'' is a unique sake cup that imitates a piece of armor that completely covers the body from the tip of the chin to the cheek, making it appear as if one is wearing armor when drinking sake.
The motif is a piece of armor known as a ``kawari kabuto,'' which has a unique and unique design and is said to have been worn by warlords from the Sengoku period. Koga was inspired to create this work because he was impressed by the way these men risked their lives on the battlefield, but also competed for their unique beauty.

Koga calls the modern age, where the development of SNS has made it possible for everyone to have a voice, an era of inferiority. ``If you have the will and determination to pioneer the times, you can rise to the top regardless of your origins.'' Koga continues to send encouragement to today's high-minded military commanders by creating the Cheek Armor Cup.

Among the many cheek armor series, this one is themed around Takeda Shingen, a representative legendary Sengoku warlord. It features a menacing tiger's mouth, inspired by its nickname, "Tiger of Kai." It is paired with a work based on Uesugi Kenshin, who is nicknamed the ``Echigo Dragon.''