Touma Kusaka is part of a clan intent on expelling foreigners from Japan, a view he personally disagrees with. He first meets Keiichirou Akizuki during a failed attempt to prevent his clan members from burning the British Embassy, and during their second meeting persuades Akizuki to teach him English. Eventually Kusaka is offered the opportunity to go to Great Britain for several years, and confesses his feelings to Akizuki just before he goes.
When he returns, both their clans have switched viewpoints and are embroiled in the Boshin War. Kusaka obtains a high-ranking position and searches for Akizuki at every fight he is in. When he finds Akizuki on the battlefield, about to commit suicide, he stops him, kills the only witness, and sneaks him away. Akizuki is unable to escape but still determined to commit suicide, grieved that Kusaka would commit murder for him. Kusaka on the other hand is determined to keep Akizuki alive at all costs.
The series provides examples of:
- An Arm and a Leg: Akizuki loses his left leg during a battle.
- Bishonen: Kusaka, Akizuki and Aizawa.
- Boys Love Genre
- Conflicting Loyalty: Set during the great Boshin civil war in Japan (1864 to 1869). Akizuki is on the isolationist side (expel foreigners and keep the Shogunate system) and Kusaka is on the imperialist side (open the borders and embrace modern culture). Somewhat subverted in that both main characters want to keep the borders open
- "Dear John" Letter: Akizuki left one for Kusaka.
- Death Is Dramatic: Understatement.
- Death Seeker: Akizuki.
- Death Wail: Kusaka does this when Akizuki commits suicide.
- Disabled Love Interest: Akizuki became this when he lost his left leg.
- Disabled Means Helpless: Kusaka won't let Akizuki do anything himself due to the loss of a leg and the fact he could use anything around him to end his life.
- Downer Ending: Akizuki successfully commits suicide and Kusaka soon follows.
- Dressing as the Enemy: Inverted when Kusaka dresses Akizuki as a Chōshū clan member so he may get away and be treated for his injuries.
- Face Death with Dignity: This is what Aizawa convinces Akizuki he must do and hands him a knife to commit seppuku.
- Gayngst: The two lovers cannot be together because of social circumstances (from being on opposing sides during the Boshin War to the typical prejudices against homosexuality).
- Hey, It's That Voice!: Sephiroth is Akizuki.
- Highly-Conspicuous Uniform: Kusaka while fighting in the war. One wonders how in the heck they could even fight with those helmet-hair thingies.
- Jidai Geki: The arc is set in the Bakumatsu/early Meiji era.
- Leave No Witnesses: Arguably Kusaka's Moral Event Horizon which shocked Akizuki.
- Pull the Thread: Aizawa did this to Kusaka when he suspected Kusaka was lying about his accounts following the battle he found Akizuki injured.
- Secret Relationship: Kusaka certainly tried everything he could to keep his relationship to Akizuki secret from the rest of the Chōshū clan.
- Seppuku: Akizuki goes through with it, and then so does Kusaka.
- Show Within a Show: The OVA / Manga series Haru wo Daiteita is the story of two contemporary adult video actors filming a movie based on Winter Cicada. Even more, in-universe, Winter Cicada did actually happen (as in, Kusaka and Akizuki really lived and died, then a nurse who knew the two of them wrote about their love story, then one of the lady's descendants found the manuscript and had it adapted in a novel...)
- Snow Means Death: Kuzaka finds Akizuki lying in the snow at the end of the final OVA.
- Subverted in the manga, where what gives away the fact that he's dead is all the blood.
- Star-Crossed Lovers: They were never going to really get a chance.
- Thou Shall Not Kill/Technical Pacifist: Kusaka was the former, became the latter during the war and then became neither...