Kako Mayama is a girl who likes playing fantasy games, especially alchemy-themed games because she likes to craft items in games. One day, she died after saving an animal that was actually the pet of a goddess from another world. The goddess gave Kako a chance to be reincarnated in another world in return for saving her pet. She would also give her the ability of her choice from a list if she accepted her offer. Without hesitation, Kako accepted the offer and chose Alchemy ability from the listー No. To be exact, she wanted the Alchemy ability from the list, but because of some kind of careless mistake, she got Synthesis ability instead. Kako was disappointed at first but then she realized the greatness of her ability. Synthesis ability is kind of similar to Alchemy ability, but they have differences. To make an item using Alchemy, you need to collect the required materials first, but to use Synthesis ability you only need multiple items to be combined together into a higher grade item. When Kako realized the usefulness of her ability, she started to combine cheap items to create high-quality items and achieve a successful life. After a while, she became completely addicted to her game-like ability. She kept creating extraordinary items one after another and making a sensation around the world.