The overall and final message of this story is absolutely touching. The message and theme the author puts out is extremely relatable, heart-wrenching, and puts a pit in your stomach thinking about regret of what could have been. However the manga doesn't focus on just displaying this message, it also has its own sci-f survival setting. Honestly, I didn't find the setting and incidents within the story to be all so charming or beautiful. The world and characters were unlikeable, disturbing, strange many times. The main character and the girl(Kaho) he loves are amazing characters, and the girl is drawn beautifully as well. Kaho is one of the best female character designs I've ever seen. If you're a fan of his works, definitely check this manga out, it has good reread value and its strengths definitely outweigh the flaws.