It's really a great novel 9/10 because >
However, one thing is certain, the MC swapped his brother's place with his life in that Black Bird World. So till the end now it's an AI-MC which is funny xD. .
Still, I liked the story and the characters. I felt through its novel's characters some relation to our feelings about sadness, anger,/ happiness > to the things we have; and most of it, loneliness...
Warning: Rambling here!
Honestly, though the story relates to loneliness and family, never forget, a person can live with the feeling of loneliness, my opinion, maybe because of all my experience of life till now of sixteen years old

. I only have my family and only one true friend at high school, I might have been a student with other students however we mostly were... how should I call it, acquaintances or buddies, people who got used or along with each other, < I believe I fitted in that category because that's how I truly felt in low school or middle school and still do with my classmates in high school, still now it's different with a friend because its pleasant to talk to another truthfully about many things (example<<), so basically that's all my rambling xD