Chiko is a high school student who can see other people’s red threads, which is the thread that connects one person to his/her soul mate. She uses her ability as a musubi-ya to advise her schoolmates on their love lives, for a fee of course! But upon stumbling upon a hidden room at her school, she sees a mysterious looking white spool of thread that suddenly comes alive and traps her. The next thing she knows, her body has become like a ten-year old kid again and the only way to get back her body is to use the mysterious thread to expel evil spirits and become a real musubi-ya!

From Go! Comi:

Amane Kamori lives in a rural village, isolated from modern society. She is a powerful medium, able to control living creatures and things through the use of its real name. Her main companion is Hyoue, her guardian demon dog, who she powers up through kissing. Forbidden from revealing her identity, she and Hyoue are allowed to move to Tokyo. Together they work to help both the living and the dead deal with various troubles, while also adjusting to high school society. Amane must deal with jealousy from classmates, who don't understand why the handsome Hyoue is so devoted to her, as well as with her own family attempting to force her to come home. The family even attempts to break her bond with Hyoue. Meanwhile, Hyoue devotes himself to his master, while struggling to hide the forbidden feelings he has for her.

Summary from Go! Comi:

Miharu hasn't been having a good year. Her mother died, leaving her only a single ring to remember her by, and her father went bankrupt – leaving her with all his debts! Though she intended to sell the ring to pay off her debts, a run-in with a hot boy and a brush with alchemy leave her unable to part with it...literally!