Dark to Light Relationship is to be understood figuratively.

There are in the VN two characters that all opposed who gradually become lovers, like rivals / enemies who fall in love.

To use this tag at best, we must focus on the type of relationship between the two characters: it is imperative that the characters do not love each other at first (but they can feel respect or have the admiration for others) and / or having just a carnal relationship.

So other types of similar relationships can be included as Sex Friends who become lovers.

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Unfortunate title, convoluted description. No reason to create such an umbrella tag and throw a kitchen sink under it. There are other tags that can be used in its place: g275, g1097 and similar.