Haruo Koga

Koga's mother had made curry, but strong vibrations made the ground rumble, causing many things to fall, and then part of the ceiling fell on her, killing her instantly in front of Koga, which left him alone... Until he met the Muto again at the sanctuary.

After the first devastating earthquake, Haruo heads to the shrine on the hill, where Koichiro shines a light to lure his family to a nearby shrine, along with anyone else who happens to be passing by. He locks himself in his room, sits by a tree, and listens to music with his headphones.

Koga follows the group throughout the disaster until they retrieve a memory card containing important data from Onodera's base, which gets stuck on a platform. Koga decides to use his speed to retrieve the card and run back in 10 seconds. Unfortunately, waves sweep him away before he can reach safety, after he throws the card to Ayumu. (But they can change his fate and save him if they want, or not.)

Haruo Koga (古賀 春生, Koga Haruo) was a 17-year-old boy who lived with his mother near the Mutoh family. He was an ace in athletics and was also known for his musical talent. Koga used to live with the Mutohs; they ate together and played board games together, which is why Ayumu was very fond of him. But later, they stopped talking and drifted apart.

Haruo Koga: A tall, slender young man with black hair and glasses. Intelligent, reserved, and observant, he usually remains calm even in extreme situations. Although he may seem cold or distant, he is very kind, empathetic, and protective of those he cares about. He thinks before he acts and prefers to solve problems logically. Mari Mutō: Mother of Ayumu and Gō. She is a loving, responsible, and very protective woman towards her family. She tries to maintain hope and support her children even when all seems lost. Kōichirō Mutō: Father of Ayumu and Gō. He is a hardworking, calm, and optimistic man. He deeply loves his family and always tries to protect them, even sacrificing himself if necessary. Ayumu Mutō: The protagonist of the story. An athletic, determined, and very resilient teenager. At first, she may seem impulsive, but as the story progresses, she develops great mental and emotional strength. Gō Mutō: Ayumu's younger brother. He is a curious, innocent, and very cheerful boy. He admires his family and, despite the disaster he is experiencing, tries to maintain his optimism. Kite: A foreign traveler and influencer. He's relaxed, friendly, and optimistic. He likes to record what's happening around him and usually lifts the group's spirits with his positive attitude, though he also shows courage when the situation calls for it. Nanami Shiomi: A kind and considerate young woman. She has a calm and empathetic personality. She's the one who gets Koga new glasses, showing her concern and affection for him.