2045年5月。東京大学に入学した大学1年生の薪剛は、両親の死の真相を知るため、唯一の手掛かりである東京大学経済学部国際思想史学科、通称「プレミアム」総本山(ヘッドラウンジ)に近づこうとしていた。徹底したセキュリティのもと、会員しか入れない「プレミアム」総本山に侵入するには、東京大学入試で優秀な成績をおさめ、次期会員に選ばれる必要がある。新入生のなかで鈴木克洋を次期会員の有力候補と見込んだ剛は克洋に近づくものの、悪気なく無礼な態度をとり克洋を怒らせてしまう。しかし、やがて剛の事情を知った克洋は協力することを決意。2人はそろって「プレミアム」総本山内部への侵入を試みるが、剛の両親には、剛も知らない秘密があった。
May 2045. Tsuyoshi Maki, a first-year student at the University of Tokyo, is trying to approach the only clue he has to find out the truth behind his parents’ death: the Department of International Intellectual History at the Faculty of Economics of the University of Tokyo, commonly known as the “Premium” Headquarters (Head Lounge). In order to enter the “Premium” Headquarters, which is under strict security and only accessible to members, one must achieve excellent results in the University of Tokyo entrance exam and be selected as the next member. Tsuyoshi sees Suzuki Katsuhiro as a strong candidate for the next member among the new students, so he approaches Katsuhiro, but he unintentionally behaves rudely and angers Katsuhiro. However, after learning about Tsuyoshi’s situation, Katsuhiro decides to cooperate. The two try to enter the “Premium” Headquarters together, but Tsuyoshi’s parents have a secret that even Tsuyoshi does not know.