Tsundere Majo wo Korose, to Megami wa Itta

"I was proud to be the biggest tsundere fan in the world until the day everything changed: when I woke up from uneasy dreams to find myself turned into a staff and buried in a forest! Fortunately for me, a narrow-eyed, silver-haired beauty saved me. I tried to thank her, only for her to say...it's not like she saved me for my sake, or anything! What is that but the textbook line of a tsundere?! This perfect tsundere specimen is apparently Stella, a student of the Saint Antohsa Academy and the owner of a certain holy magic staff—me. Guess I'll have to cheer her on for the rest of my life! But wait, why am I a staff, anyway? When I visit the Goddess who rules over this world in the hopes of becoming human again, she tells me I need to kill Stella, the so-called evil witch, to have my wish granted! I have to choose between my shy beloved and world peace? Well, that's an easy one...

(Source: J-Novel Club)