Edo Castle in the context of Moat

The Imperial Palace (皇居, Kōkyo; lit. 'Imperial Residence') is the main residence of the emperor of Japan. It is a large park-like area located in the Chiyoda district of the Chiyoda ward of Tokyo and contains several buildings including the Fukiage Palace (吹上御所, Fukiage gosho) where the emperor has his living quarters, the main palace (宮殿, Kyūden) where various ceremonies and receptions take place, some residences of the Imperial Family, an archive, museums and administrative offices.

The 1.15-square-kilometer (0.44 sq mi) palace grounds and gardens are built on the site of the old Edo Castle.

The Tokugawa shogunate, also known as the Edo shogunate, was the military government of Japan during the Edo period from 1603 to 1868.

The Tokugawa shogunate was established by Tokugawa Ieyasu after victory at the Battle of Sekigahara, ending the civil wars of the Sengoku period following the collapse of the Ashikaga shogunate. Ieyasu became the shōgun, and the Tokugawa clan governed Japan from Edo Castle in the eastern city of Edo (Tokyo) along with the daimyō lords of the samurai class.

Yūrakuchō (有楽町) is a business district of Chiyoda, Tokyo, Japan, situated in between the Ginza and Hibiya Park, southeast of the Tokyo Imperial Palace. The district takes its name from Oda Nagamasu (1547–1622), who was also known as Yūraku (有楽). Oda Nagamasu built his mansion here on land granted by Tokugawa Ieyasu near the Sukiya-bashi Gate of Edo Castle. The place name dates from the Meiji period.

Yūrakuchō is served by several train and subway stations, including Hibiya Station (Toei Subway and Tokyo Metro lines) and Yūrakuchō Station (JR East and Tokyo Metro lines).

Tokugawa Ieyasu (born Matsudaira Takechiyo; January 31, 1543 – June 1, 1616) was a Japanese samurai, daimyo, and the founder and first shōgun of the Tokugawa shogunate of Japan, which ruled from 1603 until the Meiji Restoration in 1868. He was the third of the three "Great Unifiers" of Japan, along with his former lord Oda Nobunaga and fellow Oda subordinate Toyotomi Hideyoshi. The son of a minor daimyo, Ieyasu once lived as a hostage under daimyo Imagawa Yoshimoto on behalf of his father. He later succeeded as daimyo after his father's death, serving as ally, vassal, and general of the Oda clan, and building up his strength under Oda Nobunaga.

After Oda Nobunaga's death, Ieyasu was briefly a rival of Toyotomi Hideyoshi, before declaring his allegiance to Toyotomi and fighting on his behalf. Under Toyotomi, Ieyasu was relocated to the Kanto plains in eastern Japan, away from the Toyotomi power base in Osaka. He built his castle in the fishing village of Edo (now Tokyo). He became the most powerful daimyo and the most senior officer under the Toyotomi regime. Ieyasu preserved his strength during Toyotomi's failed attempts to conquer Korea. After Hideyoshi's death and the Battle of Sekigahara, Ieyasu seized power in 1600.

Ushigome (牛込) is a neighborhood in Shinjuku, Tokyo, and a former ward (牛込区 Ushigome-ku) in the now-defunct Tokyo City. The name Ushigome refers to a former cattle ranch in the area that was next to a horse ranch, Komagome (駒込). In 1947, when the 35 wards of Tokyo were reorganized into 23, it was merged with Yotsuya ward of Tokyo City and Yodobashi suburban ward of Tokyo-fu to form the modern Shinjuku ward.

Ōta Dōkan (太田 道灌; Japanese pronunciation: [oː.ta (|) doꜜː.kaɴ], 1432 - August 25, 1486), also known as Ōta Sukenaga (太田 資長), was a Japanese samurai lord, poet and Buddhist monk. He took the tonsure as a Buddhist priest in 1478, and he also adopted the Buddhist name, Dōkan, by which he is known today. Dōkan is best known as the architect and builder of Edo Castle (now the Imperial Palace) in what is today modern Tokyo; and he is considered the founder of the castle town which grew up around that Ōnin era fortress.

Saigō Takamori (Japanese: 西郷 隆盛; 23 January 1828 – 24 September 1877) was a Japanese samurai and politician who was one of the most influential figures in Japanese history. He played a key role in the Meiji Restoration, which overthrew the Tokugawa shogunate in 1868, and subsequently served in the new Meiji government. However, he later became disillusioned with the direction of the new regime and led the Satsuma Rebellion against it in 1877, in which he was killed.

Born into a low-ranking samurai family in Satsuma Domain, Saigō rose to prominence as a retainer of Shimazu Nariakira, the daimyō of Satsuma. He was involved in national politics in Edo and Kyoto, advocating for shogunal reform and a stronger imperial role. After Nariakira's death, Saigō was exiled twice, first to Amami Ōshima and then to the harsher Okinoerabujima, periods during which he developed his political and philosophical ideas. Pardoned and recalled, he played a crucial part in forging the Satchō Alliance between Satsuma and Chōshū Domain, which was instrumental in the shogunate's downfall during the Boshin War. Saigō commanded imperial forces and negotiated the bloodless surrender of Edo Castle.

Sankin-kōtai (Japanese: 参覲交代/参覲交替, now commonly written as 参勤交代/参勤交替, 'alternate attendance') was a policy of the Tokugawa shogunate during most of the Edo period, created to control the daimyo, the feudal lords of Japan, politically, and to keep them from attempting to overthrow the regime. It required most daimyo to alternate between living in their domain and in the shogunate's capital, Edo, every year. This made the daimyo subject to constant surveillance from the shogunate. This also forced the daimyo to have residences in both their domain and Edo. The cost of maintaining several lavish residences as well as the journeys to and from Edo was a constant drain on the finances of the daimyo, which greatly increased the shogunate's control over them and kept them militarily weak. The daimyo were also required to keep their wife and children in Edo permanently to act as hostages.

Lady Kasuga (春日局, Kasuga no Tsubone; 1579 – October 26, 1643) was a Japanese noble lady and politician from a prominent Japanese samurai family of the Azuchi–Momoyama and Edo periods. Born Saitō Fuku (斉藤福), she was a daughter of Saitō Toshimitsu (who was a retainer of Akechi Mitsuhide). She was the wet nurse of the third Tokugawa shōgun Iemitsu. Lady Kasuga was one of the best politicians in the Edo period. She stood in front of negotiations with the Imperial Court and contributed to the stabilization of the Tokugawa Shogunate.

Kasuga was one of the most powerful figures in the Ōoku (the quarters in Edo Castle where the women related to the Shogun family resided) . She is counted alongside Matsudaira Nobutsuna and Yagyu Muneyori as one of the Three Tripod Legs, who supported and propped up Iemitsu.

Tenshu (天守, 天主, 殿主, 殿守, also called tenshukaku; 天守閣) is an architectural typology found in Japanese castle complexes. They are easily identifiable as the highest tower within the castle. Common translations of tenshu include keep, main keep, or donjon.

Tenshu are characterized as typically timber-framed, having multiple stories, being seated on ishigaki (dry stone) foundations, and having individual floors delineated by surrounding tiled eaves. Further, tenshu are typically decorated with varying patterns of dormer gables (chidori-hafu), and are capped with hip-and-gabled roofs (irimoya-hafu) with shachihoko finials. Not all Japanese castles originally possessed tenshu (e.g. Sendai), many well-known castles have lost their tenshu (e.g. Nijō, Edo), many have had the tenshu rebuilt on multiple occasions (e.g. Nagoya, Osaka).

The Nihonbashi River (日本橋川, Nihonbashi-gawa) is a river which flows through central Tokyo, Japan. It is a distributary river of the Kanda River and flows into the Sumida River near the Eitai Bridge.

The river is 4.8 km (3.0 mi) in length and passes through Chiyoda and Chuo wards. The river was created by a re-channeling of the former Hira River in the 15th century at the direction of Ōta Dōkan to form a part of the external fortifications and water management plan for Edo Castle.

The Ōoku (大奥, "great interior") was historically the women's quarters of Edo Castle, the section where the women connected to the reigning shōgun resided. Similar areas in the castles of powerful daimyō, such as the Satsuma Domain, were also referred to by this term.

During the reign of the second shogun, Tokugawa Hidetada, Ōoku was established in Edo Castle as a women's room where his official wife (御台所, Midaidokoro), Oeyo, resided. During the reign of the third shogun, Tokugawa Iemitsu, the Ōoku was expanded at the suggestion of his nanny, Lady Kasuga, to ensure the birth of a male heir to the shogun's lineage, and became a vast shogun's harem with nearly 1,000 women working as maidservants.

Yagura (櫓, 矢倉) is the Japanese word for "tower", "turret", "keep", or "scaffold". The word is most often seen in reference to structures in Japanese castle compounds but can be used in other situations as well. The bandstand tower erected for Bon Festival is often called a yagura, as are similar structures used in other festivals. Yagura-daiko (taiko drumming from atop a yagura) is a traditional part of professional sumo competitions.