Two AV actors audition for the same role and are later cast together in the TV adaptation of the film. Katou falls for his older co-star, Iwaki, immediately, and is delightfully persistent in his courtship. Which basically consisted of showing up at his house and eventually moving in. They're open about their relationship with the public and their families; they marry; they deal with the sort of ups and downs that come up in a long-term relationship.
I didn't expect to like this story. The art style in the early chapters threw me, but it evolves as the story goes along. Katou is easily the prettiest man in any manga I've read. If he weren't married to Iwaki, I'd say he's one of my husbands, but I respect their relationship too much.
A couple icky things happen to them, which are caused by outside people, but their relationship is solid and honest and loving. They love each other SO MUCH. That's what I like most about this.
This story DOES have a sequel, which I've tagged with this story's name as well. It is ongoing.
ETA 2020: It's probably best to avoid the sequel! Just read this and pretend this is all that exists!
Haru wo Daite Ita