2.43: Seiin Kōkō Danshi Volley-bu First Season (2.43 清陰高校男子バレー部 2.43 Seiin Kōkō Danshi Barē-bu, 2.43 Seiin High School Boys' Volleyball Team) is the first arc of the 2.43: Seiin Kōkō Danshi Volley-bu novel series. It was first released as a tankobon volume on July 26, 2013, and then released as two bunkobon volumes in 2015.
After Kimichika Haijima drove his teammate on his Tokyo middle school's powerhouse volleyball team to attempt suicide, he relocates to his mother's hometown, Fukui, where he spent his childhood, and reunites with his childhood friend, Yuni Kuroba.
Kuroba, who has outstanding physical abilities but is weak under pressure, and Haijima, whose overwhelming passion and talent for volleyball causes friction with those around him, grow into an ace duo.
However, the two clash at their final middle school prefectural tournament. With their friendship broken off, the two eventually go on to their local Seiin High School together.
They meet the uneven duo of Oda, the 163cm hot-blooded captain and Aoki, the 193cm cool-headed vice captain, as well as the second-year Kanno, who is allergic to sunlight and always wears long-sleeved shirts and pants. Kuroba and Haijima are aiming for the Nationals in volleyball once again, but...
- Prologue: Cold Fingers (冷たい指 Tsumetai Yubi)
- Chapter 1: The Boys, Yunichika (少年ユニチカ Shounen Yunichika)
- Chapter 2: Dracula and Princess Briar Rose (ドラキュラといばら姫 Dracula to Ibara-hime)
- Chapter 3: The Dog's Line of Sight and the Giraffe's Line of Sight (犬の目線とキリンの目線 Inu no Mesen to Kirin no Mesen)
- Chapter 4: Drifting Yunichika (漂流ユニチカ Hyouryuu Yunichika)
- Chapter 5: Stand by Me (スタンド・バイ・ミー)
- Epilogue: To Connect (つなぐ Tsunagu)