Tōseigusoku (Japanese: 当世具足, lit. "modern armor") is a collective term for Japanese armors that were common from the end of the Muromachi period and during the Azuchi-Momoyama period, i.e., during the Sengoku period or in the 16th century.
The term tōsei, "modern," was given to the armor types of this time to distinguish them by name from the usual armors such as Dōmaru and Haramaki. The main reason for the development was changes in war tactics, advancements in weapon technology, including the introduction of the rifle, and the influence of Western armors that came to Japan with the Nanban trade.
The Sengoku period brought new demands on armor construction: in order to equip large armies, armors should be easy to produce and comfortable to wear without extensive training. The introduction of firearms, on the other hand, demanded armors capable of protecting against bullets. Therefore, various new construction methods were adopted based on connected segments.
The high demand for war equipment of this time led to a variety of different armor types, the most important being Okegawadō (桶側胴), Nanbandō, Hotokedō (仏胴), and Mogamidō (最上胴), but also the Tatamidō.
For the construction of the Dōmaru, which has been used since the Heian period, leather plaques reinforced with iron, so-called Kogane (小札), were used, which were connected both horizontally and vertically with cords. This manufacturing method required elaborate handwork.
To simplify this work, larger segments were used, either wider iron-clad leather strips, so-called Itazane (see below), metal strips, or even (following European model) chain mail as in the Tatamidō or a cuirass as in the Nanbandō.
To enhance the protective effect, the breastplate was constructed in three parts: a stomach protector (長側, nagakawa), a chest protector (前立挙, mae-tateage), and a back protector (後立挙, ushiro-tateage).
The armor was supplemented by the face protector Mempō (面頬), the thigh protector Haidate (佩楯), and others. The predecessor, the Dōmaru, was only two-piece.
A Tōseigusoku also included a helmet (Kabuto). With these, too, there was a variety of shapes, some with very ornate decorations. Not only the purely practical use played a role, but it also reflected the social and military status and the individual character of each warrior (Bushi).