April 3, 1971

Kamen Rider Den-O: April 3, 1971 (仮面ライダー電王 -1971年4月3日-) is the S.I.C. Hero Saga side story published in Monthly Hobby Japan magazine for Kamen Rider Den-O. Running from December 2008 to October 2009, the story expands upon the events of Climax Deka and Kamen Rider Nega Den-O's travel through time joining forces with the Great Leader of Shocker, with Den-O and Zeronos joining forces with the original Shōwa Kamen Riders to fight them. It features original characters Negataros Spirit Form (ネガタロス精神体) and Negataros's form as Great Leader Ganseki (岩石大首領).
 * Chapter titles
 * 1) Imagin Revival (復活のイマジン)
 * 2) Negataros Army (ネガタロス軍団)
 * 3) Shocker Leader (ショッカー首領)
 * 4) The Capture of Yuto Sakurai (囚われの桜井侑斗)
 * 5) Five Plus One (５＋１)
 * 6) Comrade (仲間)
 * 7) True Form (正体)
 * 8) Great Leader Ganseki (岩石大首領)
 * 9) Seven Riders (７人ライダー)
 * 10) Ten Riders (１０人ライダー)
 * 11) From the Window of the Den-Liner (デンライナーの車窓から)