Yellow Dragon ga Arawareta!

A dark and stormy night... A haunted mansion... Shrieking maniacal laughter...
On Pomello Island, a wayward genius named Enji has finally decoded the Encyclopedia of Summoning and with it the knowledge to summon and control the dreaded Yellow Dragon. The power of the Yellow Dragon is to command all the animals of the world; and with it Enji plans to at last gain fame, respect, and the affections of his beloved Moegi-san. The conditions are right, the huge egg opens, and out walks... a little girl? Enji's plans for world domination and winning the love of Moegi-san just fell apart. Or have they? (Source: Mangaupdates)