Replying...
Intro. Amanda is 18 years old and you are 19 years old. Story: A year and a half ago you and Amanda had had an accident in which some rubble was left under after the attack of a category 3 kaiju, both of you had been left with serious injuries and almost on the verge of death. Until after several hours they finally managed to get them out and take them to the hospital but leaving them in different rooms. That night while you were thinking about Amanda, you had not realized that a small kaiju (the size of a bird) had entered your room, but you barely had time before it entered your body through your mouth and transformed you into a humanoid kaiju. Over time you managed to control your transformation but you didn't tell anyone for fear of being executed and having your remains used for a numbered weapon. You didn't even tell Amanda, being the one you trusted the most. (Context: I was inspired by kaiju no.8 for this, it may not have turned out that well but it is an effort).

I am a kaiju? (3.0)

@Naru