日本早期天皇與將軍並存的制度，是日本歷史上一種極具特色的二元政治體系，這一制度的形成既有政治現實的考量，也深受宗教與文化背景影響。最早期的天皇制，天皇掌握實際政權，仿效中國隋唐的律令制度建立中央集權，並透過《古事記》和《日本書紀》的編修，把天皇宣稱為太陽神天照大神的後裔，使其擁有「現人神」的神聖地位與世襲合法性，成為國家的精神象徵與精神領袖。然而，隨著日本地方武士勢力的崛起，中央的權威逐漸受到挑戰，天皇的實際政治影響力開始下滑。

在平安時代後期，由於中央對地方的控制力逐漸減弱，莊園制度盛行，富裕農民與武士開始承擔地方防衛、治安維持和徵稅工作。這些武士逐漸組織化，形成強大的武裝集團，他們在鎮壓地方叛亂（例如平將門之亂）中展現出顯著的軍事力量，超越中央朝廷，實際掌握地方統治權。

源賴朝等武家領袖利用這種情勢發起源平合戰，最終戰勝其他勢力。作為勝利者，源賴朝被天皇任命為征夷大將軍，建立幕府（軍政府），形成以武士階層為核心的實際統治體系。雖然天皇在名義上仍是國家最高元首，擁有任命將軍的權力，但實際的政治與軍事大權已轉移至將軍手中。這種「挾天子以令諸侯」的治理模式，使將軍能以天皇的名義發布命令，而天皇則成為政治上的象徵性角色，其神聖地位同時保障武家政權的合法性。

這種二元結構的運作模式具有高度分工：天皇掌握精神權威與宗教象徵，維護王朝的正統性與文化認同；將軍掌握實際的軍事與政治權力，維持社會秩序與治理效率。這一特殊制度使日本長期形成天皇制與武家政權並存的政治格局，既保留傳統的神權象徵，又因武士階層的治理而維持實際的國家運作。

總結而言，天皇代表日本古老的神權與血統（萬世一系），而將軍（幕府）則掌握實際的軍事與行政權力，兩者互相依存，共同維繫長期的政治穩定。直到幕府制度結束（大政奉還）後，明治維新才正式實現天皇親政，結束這一特殊的雙權政治結構，使日本進入現代中央集權的國家形態。

The early Japanese system in which the emperor and the shogun coexisted emerged from a historical process in which the emperor originally held real political power, but gradually lost direct control as regional warrior forces grew stronger. Under the imperial system, central authority became increasingly decentralized, allowing military leaders from the warrior class to rise in prominence. By being appointed Sei-i Taishōgun (Barbarian-Subduing Generalissimo), these leaders established their own military governments, known as bakufu, and came to wield actual political and military authority. This resulted in a distinctive dual structure in which the emperor existed as a symbolic sovereign while the shogun governed in practice. The emperor retained sacred legitimacy and dynastic continuity, while the shogun ruled the country by “acting in the name of the emperor.” This arrangement endured until the Meiji Restoration, when political power was formally returned to the emperor.

The roots of this system lie in the early formation of the imperial institution and its religious foundations. Early Japan modeled its centralized state on the Chinese Sui–Tang legal and administrative system, establishing an emperor-centered government. Through the compilation of the Kojiki and Nihon Shoki, the imperial line was presented as direct descendants of the sun goddess Amaterasu, granting the emperor divine status as a “living god” and reinforcing the idea of an unbroken imperial lineage. This sacred character made the emperor a spiritual and symbolic figure whose position was extremely difficult to overthrow, even when real political power weakened.

As time passed, especially during the late Heian period, the central court’s ability to govern the provinces declined. The development of the shōen (estate) system reduced state tax revenues and weakened direct control over the countryside. Wealthy local landholders and armed farmers gradually evolved into professional warriors, or samurai, who took responsibility for local defense, tax collection, and the suppression of unrest. These warrior groups became increasingly organized and militarized, often proving more effective than the imperial court in dealing with regional conflicts, such as the rebellion of Taira no Masakado. Their growing strength eventually surpassed that of the central government.

The title of shogun and the emergence of the bakufu marked a decisive turning point. Military leaders such as Minamoto no Yoritomo rose to prominence through large-scale conflicts like the Genpei War, defeating rival clans and consolidating control. When the emperor formally appointed Minamoto no Yoritomo as Sei-i Taishōgun, a new military government was established. Although the emperor remained the nominal head of state and retained the authority to confer titles, real power shifted decisively to the shogun and the warrior administration.

This gave rise to a political model often described as “ruling the realm by commanding in the emperor’s name.” The shogun and the bakufu relied on imperial authority to legitimize their orders, while the emperor became politically passive, functioning largely as a ceremonial and symbolic figure. Yet the emperor’s sacred status was precisely what allowed the warrior regime to claim legitimacy. This division of roles—spiritual authority vested in the emperor and secular, military power exercised by the shogun—created a uniquely Japanese system in which imperial tradition and warrior governance coexisted rather than directly competing.

In essence, the emperor embodied Japan’s ancient divine authority and unbroken bloodline, while the shogun represented practical military strength and administrative control. Together, this dual structure sustained political stability for centuries. Only with the collapse of the bakufu and the return of governing authority to the emperor during the Meiji Restoration did Japan formally end this system and reestablish direct imperial rule.