Tokimeki Memorial ~Only Love~ OVA provides nothing major towards the original series. The first episode is some kind of an extra episode between 17-18 introducing one new character along some new scenes. The second one is basicly a recap of the main storyline.
The art, sound and character remained exactly the same. The enjoyment dropped a little and is no where as good as the series. I found it very interesting to watch the recap episode and telling me what the main storyline actually was since I forgotten it.
