This particular OAV is among my favourites because it's a recap of the story between Enjouji and Ranmaru. It depicts the deciding moments in their lives that led them to go from friends to lovers, and it shows how their relationship has just become stronger as time goes by. It also questions their future as Ranmaru realizes the “disadvantages” of having a male partner.
Contrary to its predecessors, this installment has lighter yaoi content, but there is no doubt all the elements that make Kizuna are still present.

Seikimatsu Darling is the story of two men who fall in love, but neither is willing to be the uke (bottom) so they plan a trip to a hot spring to solve their dilemma. As you can see, the plot is pretty simple but perfect for a comedy.
Unfortunately, the two main problems are the run time (30 minutes) and the average animation, though you must also keep in mind this is a pretty old OVA.
I addressed the duration of the OVA because there is a nice deal of information that has to be transmitted in 30 minutes and it obviously isn’t enough time. Hence, the story looks “hurried” and it has some abrupt scene changes that may be confusing, but all-in-all, I think it defends itself quite well.
It has no sex scenes, but it is ideal if you want to watch something light and funny.
As a side note, I highly recommend the manga, since it provides more information and character development.

After a fortuitous event, a middle-aged man enters a contract with a demon. The demon won't leave unless Kai Hisae makes a wish, but he doesn't need anything more than what he already has...or does he?
If you are a Naono Bohra fan, this work will not disappoint you; it mixes once more the supernatural elements with the romantic ones to bring us an amazing story in the way only Naono Bora is capable of.
Her art is incredible and her plot intriguing, for it is possible that there is a grater reason as to why the main characters were bound to meet.