Kagetsu Tohya consists of "Twilight Glass Moon, Fairy Tale Princess", the long main story with many branches, and several shorter side stories that are unlocked one after another after related events in the main story have been read. Ten of these side stories are combined as "Ten Nights of Dream".
Twilight Glass Moon, Fairy Tale Princess
One year after the events of Tsukihime, Shiki is a victim of an accident. After this accident, Shiki awakens into a strange dream wherein he repeats the same day over and over. There are infinitely many endings to the day, but it always begins anew after each day. Eventually, Shiki discovers that he must find Len, the creator of the dream, if he wishes to escape.
The gameplay is exactly the same as in Tsukihime. However it uses a slightly different system in which the player goes through each of Shiki's "days" in the dream. The number of choices the player is presented with in Kagetsu Tohya is also significantly larger than in Tsukihime.
The plot is also rather flexible. Certain choices can cancel out facts that have been previously stated. For instance, Shiki can choose to leave for school early, and ponder on whether or not to go with Akiha. If he chooses to go with Akiha, they attend the same school. However, should he choose to go alone, Akiha is revealed to attend a different school from his.
Ten Nights of Dream
The first seven of these stories were written by Kinoko Nasu like the rest of Kagetsu Tohya, while the last three are contribution works by others, essentially fanfiction. It is unknown if any of these stories are to be considered canon.
- Good luck, Ciel-sensei
- Ciel teaches the rest of the cast in her role as Ciel-sensei from Tsukihime. The story is mainly a comedy story, reflecting on parts of the series in the form of questions.
- A Story for the Evening
- Akiha solves a mystery in her boarding school. This story is a sequel to her true ending in Tsukihime.
- Crimson Moon
- A look at Arcueid's history as a True Ancestor, and her first fateful meeting with Roa. This story has Roa as the protagonist and shows him in less of an antagonistic light.
- Red Demon God
- The story of Shiki's father Kiri Nanaya. This story reveals much about the Nanaya family and the Demon Hunter Organization that they are connected with.
- Nanako-chan SOS
- Nanako (the spirit of the Seventh Holy Scripture) escapes from Ciel and hides out at Arihiko's place. This story has Arihiko as the protagonist and reveals how he and Shiki met in the past.
- Flower of Thanatos
- Erotic story that takes place in an artificial dream world where Shiki, Kohaku and Hisui live in the isolated Tohno mansion.
- Hisui-chan, Inversion Impulse!
- Hisui goes insane with hilarious results. Takes place after Hisui's Good Ending.
- The Tohno Family Con Game
- Nearly the whole cast plays an elaborate game of tag for Kohaku's sake.
- Dawn (or Daybreak)
- The continued story of the girl that gets devoured in the park by Nrvnqsr Chaos in Tsukihime. Takes place after Arcueid's Good Ending. This story was written by Maruyama Kugane, the author of the Light Novel series Overlord.   
- Summer Festivals
- Five short scenes in which Shiki takes either Arcueid, Ciel, Akiha, Hisui or Kohaku on a date to the summer festival.
- Drinking, Dreaming Moon
- This hidden story, unlocked after all other content in the game has been viewed, has Shiki meeting his adoptive brother SHIKI and discussing their relationship on friendly terms.
While some of the following characters were briefly mentioned in Tsukihime, they appear with larger roles in Kagetsu Tohya:
- Len (レン, Ren?)
- Len is a former familiar under Arcueid's care, sometimes referred to as a succubus. She is not contracted to Arcueid, and is currently an independent existence. She can take the form of a pre-pubescent girl or a black cat. Her only appearance in Tsukihime is to grant Shiki a dream of a sexual encounter.
- Akira Seo (瀬尾 晶, Seo Akira?)
- Akira is an underclassman of Akiha's. She has minor precognitive powers, and previously appeared on the Tsukihime PLUS-DISC.
- Souka Tsukihime (月姫 蒼香, Tsukihime Sōka?)
- Akiha's roommate at her private school. Rather punkish. Shiki thinks she's a guy.
- Hanei Misawa (三澤 羽居, Misawa Hanei?)
- Akiha's other roommate at her private school. Slow-witted, conscientious, thorough and good at fixing things. She also happens to have the biggest breasts of any character (Major and minor) in Tsukihime.
- Tsukasa Shijyou (四条 つかさ, Shijyō Tsukasa?)
- Another student at Akiha's school. Thought she could blackmail Akiha over a love letter, and paid for it.
- Seven (Nanako) (セブン〔ななこ〕, Sebun〔Nanako〕?)
- The spirit of Ciel's most powerful weapon, Seventh Holy Scripture. She has the appearance of a little girl with some horselike features (for example hooves and a tail). Likes carrots.
- Tonami Kugamine (久我峰斗波, Kugamine Tonami?)
- Head of the Kugamine family, which has ties to the Tohno family. Was Akiha's fiancee up until the events of Tsukihime, where the engagement was cancelled and he was kicked out of the Tohno mansion when Shiki returned.
- Kouma Kishima (軋間 紅摩, Kishima Kouma?)
- A man who worked with Makihisa Tohno to attack the Nanaya clan. He fought and killed Shiki's father Nanaya Kiri.
- Kagetsu Tohya at TYPE-MOON's official website.
- Overlord Volume 1 Author Thoughts: Although there was a case of giving up the dream to be a novelist in my introductory published work, that is the adoption of my short story ’Dawn’ in Kagetsu Tohya,
- Overlord Manga Bonus Interview: Maruyama: The mini-scenario I submitted for Kagetsu Tohya ’Dawn’, got picked up, but that was fourteen years ago, and I hadn’t written anything since then. Oshio: So was doing that project for Type-Moon what got you started writing stories? Maruyama: At the time, I just liked Type-Moon games. And they just so happened to be looking for stories to include in Kagetsu Tohya, so I thought Okay, I’ll give it my best shot!
- Arcadia 2878: Old fans of Type Moon will know it but I wrote ’Dawn’.
|Tsukihime • Tsukihime anime • Tsukihime PLUS-DISC • Kagetsu Tohya • Melty Blood • Melty Blood Re-ACT • Melty Blood Act Cadenza • Melty Blood Actress Again • Hana no Miyako|
|Tsukihime -A piece of blue glass moon- • Melty Blood: Type Lumina • Tsukihime -The other side of red garden-|
|Advantage • Age of Gods • Ahnenerbe • Bajiquan • Church • Dead Apostle • Demons • Demon Hunter Organization • Familiar • Magecraft • Magical Girl • Marble Phantasm • Mystic Eyes of Death Perception • Reality Marble • Psychic • Tohno • True Ancestor • Vampire|