Will You Let Me Love You With All My Heart?

An adult romance featuring Chiyo Takamura, a 30-year-old woman who works in the civil engineering department of a major construction company. She gets confessed to by Ichika Seo – a 45-year-old man who is the vice president of a foreign company. Ichika, who is in love with Chiyo, confesses his love for her and asks her out on a date. Although Chiyo always thought of Ichika as a lunch buddy, she agreed to go out with him, and the two start a “trial” romance to see where their relationship goes.

(Source: Japanese = Wikipedia || Translation = mochibunny at MyDramaList)