TV-Series
Description
Seijirō Kikuoka initially presents as an official in Japan's Ministry of Internal Affairs and Communications, Virtual Division, though his true role is Lieutenant Colonel in the Japan Ground Self-Defense Force. He transferred voluntarily to the ministry to advance Project Alicization, a classified initiative developing artificial fluctlights—bottom-up AI—for military autonomous weapons. This project cloned newborn infant souls and accelerated societal development within the simulated Underworld.

He was one of 1,000 Sword Art Online beta testers but avoided the full launch, recognizing the technology's military potential. After the SAO incident, he participated in rescue efforts, informing Kazuto Kirigaya (Kirito) of Asuna Yuuki's hospital location. He later leveraged this connection to recruit Kazuto as an investigator for virtual incidents, establishing a pattern of manipulation.

During the Phantom Bullet arc, Kikuoka enlisted Kazuto to investigate the "Death Gun" murders in Gun Gale Online, offering financial incentives while withholding critical risks. When Asuna confronted him about Kazuto's involvement, he divulged the operation's details under pressure. Post-incident, he apologized for endangering Kazuto but continued leveraging their relationship for governmental objectives.

In Project Alicization, his manipulations intensified. He recruited Kazuto to test the Soul Translator under false pretenses, concealing the project's true military aims. After Kazuto sustained real-world brain damage, Kikuoka orchestrated his abduction to the Ocean Turtle facility to use the Soul Translator for treatment while advancing the project. He demonstrated a utilitarian view of artificial fluctlights, showcasing a copied fluctlight of colleague Takeru Higa to Asuna and Rinko Kojiro to prove its non-human status. He admitted engineering a plague in the Underworld to test residents' capacity for violating ethical taboos—a test that failed and caused significant casualties.

Kikuoka consistently prioritized human lives over artificial fluctlights, valuing one human life over 100,000 fluctlights. During the War of Underworld, his actions evolved: he faked his death during a U.S. assault on Ocean Turtle to protect a robot hijacked by Akihiko Kayaba, ensuring the Underworld's survival. Post-conflict, he vowed to protect the Underworld and its inhabitants, still hoping residents would voluntarily enlist in military service. Despite ethical compromises, colleagues like Higa noted he often chose morally difficult paths to aid allies, such as facilitating Shino Asada's visit to Kyouji Shinkawa or prioritizing Kazuto and Asuna's extraction from the Underworld against his project's interests.

His ALfheim Online alias, "Chrysheight," is a portmanteau of "chrysanthemum" and "height," reflecting a direct English translation of his surname ("Kiku" meaning chrysanthemum, "oka" meaning height). He is acknowledged as a skilled mage within the game.