Sayonara Isekai, Matakite Ashita

Keisuke awakens in a desolate world covered in ash, yet he still perceives occasional bursts of color as he moves through it. He has spent much time alone, hoping for signs of life in the empty expanse. Eventually, he encounters another person, bringing more color into his bleak surroundings. For the first time, he is not alone on his journey, and they share a common goal. Their only clue is a witch capable of answering any question, but she demands a price. The two must decide what to ask her and whether they are willing to pay whatever cost is required.