This monster's Japanese name (燦幻昇龍, Sangenshōryū) is a play on shōsangen (小三元), a yaku in Japanese mahjong, which is often translated as "little three fundamentals".
This monster's design is a two-headed dragon, reflecting how the shōsangen requires two triplets of dragon tiles, with the last dragon tile being a pair instead. Fittingly, this monster is the combined "Sangen" Synchro Monster form of "Tenpai Dragon Chundra" and "Tenpai Dragon Paidra".
Shōsangen has origins in Chinese Mahjong, where it's read as xiǎo sānyuán in Mandarin Chinese. The hand is worth 64 points in National Standard Mahjong (国标麻将 guóbiāo májiàng).