An innocent and arrogant lover

Product description ※Please note that product information is not in full comprehensive meaning because of the machine translation.

Four years ago, Kiyohiko Imaizumi, the son of a noble family of ex-peerage, who is beautiful like an angel, made an enthusiastic confession to Katsunori Hasegawa, a friend of his older brother and vice-president of a large company.
When Kiyohiko found out that for six years after the meeting, he had continued to give his devoted love to himself, who was seventeen years younger than him, he accepted that thought and became happy and loved each other.
Since then, under the pledge of Katsunori that "I will not touch anything until I become an adult," the two have continued a clean relationship.
However, Kiyohiko became impatient with his lover who really didn't touch anything even though they loved each other, and on his 20th birthday, he took a certain action as an allowance?