Death God's Agent Specchio

To keep living, a dead boy accepted a contract with a sword and became a Shinigami. The price, however, was... turning into a girl?!

"Even so, I'll clear away every foe in my path and become the strongest Shinigami!"

"Honey, if you don't flip the pan now, the food's going to burn."

"...You're so annoying!"

The first volume includes the worldbuilding. If you like to learn how the system works before reading the story, go check it out.