While Japan had been torn by war for decades, Oda Nobunaga, the first unifier, died in 1582 under the blows of his own vassal Akechi Mitsuhide. This event is an opportunity for Hashiba Hideyoshi, who defeats Akechi at the Battle of Yamazaki. Hashiba Hideyoshi must then face Tokugawa Ieyasu, another vassal of Oda, at the Battle of Nagakute. Hideyoshi then became the second unifier of Japan under the name Toyotomi Hideyoshi. Forced to the status quo, Tokugawa Ieyasu then waited for Hideyoshi's death to reaffirm his ambition. His accession to power was decided in the gigantic battle of Sekigahara. He would again force Hideyoshi's heir to commit suicide at the end of the siege of Ōsaka. The unification of the country is definitive this time and its heirs will rule Japan for 250 years.
 
Tenkatōitsu is the sequel to Kawanakajima 1561. Tenkatōitsu means Unity under Heaven. It is the name of the historical period which sees a single winner among the clans, allowing the end of the war (Sengoku Jidaï). The game focuses on the orders received by the clans of each army and the inertia of battle. The game turn is broken down into activation phases linked to the drawing of clan markers and compulsory markers (combat, movement, etc.) placed in a bowl. The system also takes into account the battle plans that each side has established before the confrontation.