Tensura Alteration: The Forgotten One

When asked "What does it mean to be forgotten?", you will most likely answer with "It means to be completely erased and/or unmemorable to anyone.", read the journey of Satoru Mikami, who was just stabbed and is on the edge of death, who meets a certain figure that embodies the word "Forgotten", and how this figure will play a key role in Satoru's new life.