Both the twins sport relatively dark skin with spiky black hair. Their earlier depictions had them with noticeably smaller eyes. Both of them wear the same Luxiole uniform and the twins share very little differences.
Service on the Elsior/Luxiole Edit
Naoru apparently served on the Elsior prior to joining Tact and Coco on Luxiole during the events of discovering ABSOLUTE and NEUE. He is part of the Bridge team from the start of the series but is not formally introduced until MK and is unnamed until EK. Naoru obtains a minor role in Kazuya's Route where he explains Coco's rank of Captain and her accomplishments where both Kazuya and Tact note his admiration toward her.
Similarly, Majiru is introduced in MK while he is not named until EK. During Kazuya's trip around the Luxiole to find out the first names of the important personnel, he mistook the twins as he thought Naoru worked both as a Bridge hand and security officer.
Both brothers share similar personalities in the short time they are shown. Previous experience in the military have them both be tough and willing in terms of physique and following orders. Naoru himself showed particular admiration of Coco's skills and accomplishments.