Sieg is an Imagin who enables DenO039s transformation into Wing Form. He arrives in the current timeline six months prior to Ryotaro becoming DenO originally intending to forge a contract with a young wealthy pregnant woman named Shiori Takayama but possesses her unborn son in the process. After the child is born and subsequently kidnapped Sieg comes into being and seeks to reunite his quotbrotherquot with their quotmotherquot crossing paths with Ryutaros and gaining access to the DenLiner. Due to his quotprivilegedquot upbringing and his already princely mannerisms Sieg becomes easily infuriated when treated with disrespect. Because he is quotbornquot in 2007 he also possesses extraordinary unique abilities. Aside from shrinking the Tars to 4 inches tall with the phrase quotKneel down to mequot Zu ga takai he also cannot be forcibly removed from Ryotaro039s body as he does not need a contract to possess humans. When possessing Ryotaro Sieg says quotDescending yet above it allhellipquot hellip Krin man o jishitehellip. He almost vanishes due to his contract holder being a newborn child and unable to form proper memories but Ryotaro is able to discover that Sieg actually made a contract with the mother to ensure her then unborn son039s safety saving Sieg039s life in the process. As his contract has been fulfilled the DenLiner takes Sieg to the date of his Shiori039s greatest memory and lives in the past freely. After his appearances in the television series he appears in the films Kamen Rider DenO: I039m Born and Saraba Kamen Rider DenO: Final Countdown allowing for the transformation into Wing Form and again in Cho Kamen Rider DenO amp Decade Neo Generations: The Onigashima Warship pestering Tsukasa039s group until brought to the climatic battle to join the Tars in forming Super Climax Form. He also appeared in ChoDenO Trilogy Episode Blue: The Dispatched Imagin is Newtral. During his first time on the DenLiner he demanded that the others call him quotPrincequot Purinsu? and asked for Hana to be his quotPrincessquot Hime? and was punched for each time he called her that. After his return Sieg refers to the Tars as his quotfamilyquot instead of his quotfriendquot phrasing. In the Imagin Anime OVA Sieg had an additional power quotSuperUltra Kneel down to mequot SpUrutora Zu ga takai? that allows him to shrink everything in sight even an entire planet. His name is given as quotZiegquot in the series039 photobook DETAIL OF HEROES: Masked Rider DenO Exclusive Photograph Collection: IMAGINE DETAIL OF HEROES IMAGINE DETAIL OF HEROES Kamen Raid Den039 Tokusha Shashinsh: Imajin? however other materials give his name as quotSiegquot such as the earlier photobook Masked Rider DenO Photobook: IMAGIN IMAGIN Kamen Raid Den039 Fotobukku Imajin?. Sieg039s physical form and name are based on swan and Prince Siegfried Jkufurto ji? from the story Swan Lake Hakuch no Mizuumi?.