Tales of Harem 4: Battle over the Hero! Sexual Cruise Climax! Virgin Vampire! (異世界ハーレム物語4 ～勇者争奪！淫行クルージング 絶潮！処女吸血姫～)
Author: Kurona Yuu [黒名ユウ]
Original Manga/Illustrations: Tachibana Omina (Circle Shimapan) [立花オミナ (サークル しまぱん)]
Label: 2D Dream Bunko (二次元ドリーム文庫)
Release Date: 10/16/2022
Naoki's quest as the Hero continues, this time by sea. The princess and the knights make a reappearance, an old friend of Leonora's captains the ship, and a vampire attacks the group.
Another entry in the Milk Series, this time with a nurse theme: Milk Nurse: Happy Boobs Hospital (ミルクナース 幸せにゅ～いん生活)
Author: Kanzaki Misora (神崎美宙)
Illustrator: Nakano Sora(中乃空)
Release Date: 5/20/2011
A boy is hospitalized with an incurable disease. Fortunately for him, a doctor there is a pioneer in the field of milk medicine and claims he can be healed by drinking breast milk. The doctor and her two nurses work to heal him and things only escalate from there.
Wing Family (ウィングファミリー) is another short story from the Thunderclaps universe.
Author: Hazawa Kouichi (羽沢向一)
Cover Illustrator: Mikan. (みかん。)
Label: Mobile 2D Dream (モバイル二次元ドリーム)
Release Date: 12/22/2005
(Cover shown above is from the 2D Petite Bunko rerelease on 1/13/2017)
Mother and daughter superheroes fight robots and protect the boy the robots were pursuing.
While nothing other than the presence of superheroes directly links this story to Thunderclaps, Swan from this story also appears at the end of Lightning Blade – Crimson, which IS confirmed to be from the same universe as Thunderclaps, so that indirectly places this story there too.
Lightning Blade – Crimson (電光鉄火 紅) is a short story from the Thunderclaps universe (TCU?).
Author: Hazawa Kouichi (羽沢向一)
Cover Illustrator: Mikan. (みかん。)
Label: Mobile 2D Dream (モバイル二次元ドリーム)
Release Date: 9/29/2005
(Cover shown above is from the 2D Petite Bunko rerelease on 9/20/2018)
A girl from Edo period Japan hunts down her father’s killer using the powers granted her by a sword passed down in her family. She discovers someone is distributing weapons from the future among Edo’s criminals.
This was only confirmed to be connected to Thunderclaps in 2021 when the MC’s indirect descendant appears in a Thunderclaps novel wielding the same sword featured in this story.
Harem Wizard Academy (ハーレムウィザードアカデミー)
Author: Takeuchi Ken (竹内けん)
Illustrations: SAIPACo.
Label: 2D Dream Bunko (二次元ドリーム文庫)
Release Date: 12/25/2008
The son of Harem Engage’s MC joins a magic school along. He finds his childhood friend there, he immediately develops a crush on his teacher, and the student council president seems to have her eye on him for due to bad blood between their grandparents.
In addition, I have included a short story providing some backstory for the teacher. It includes characters from Harem Engage and Harem Sister.
Author: Takeuchi Ken (竹内けん)
Illustrations: Ryuga Shou (龍牙翔)
Label: 2D Dream Bunko (二次元ドリーム文庫)
Release Date: 8/31/2008
A prince’s kingdom is on the run with his most trusted knight after his kingdom is attacked by the Domos army. A Domos dragon rider pursues him while he tries to regroup with his kingdom’s forces and fight back. This one is something of a crossover novel since characters from (I think) every previous entry in the series either has a cameo appearance or is mentioned in relation to the plot.