((Lol that name is my headcanon.
Ryuuzaki's and Haga's real names are not mentioned in the manga or anime. Helen (former Haga RPer) and I were bothered by that, so we decided to give them the names Furukawa Ryuuzaki and Morishita Haga. These names were carefully chosen based on their meanings:
Furukawa
古 furu (Japanese origin for "old, the past, classic, ancient")
川 kawa (Japanese origin for "river, stream, brook; flow; boil")
Ryuuzaki loves dinosaurs, so I chose a surname that had to do with ancient things. Rivers and water don't have much to do with Ryuuzaki, but I couldn't find a surname that fully fit. However, since Ryuuzaki loves dinosaurs, that also includes marine ones! xD
Morishita
森 mori (Japanese origin for "forest, woods; dark as a forest; luxuriant vegetation")
下 shita (Japanese origin for "under, underneath, below; down; inferior; bring down")
In the beginning of Duelist Kingdom, Haga led Yuugi and the others in a forest where swarms of moths flew out of the trees. In Helen's headcanon, Haga enjoys hanging out in forests and trees to observe insects. Also, Haga saw himself as a loser after he was defeated by Yami.))