You can actually read them in two different ways depending on your preference Option A: The In-Universe Chronological Order If u care about character backstory etc..read Zutto Kimi no Turn first.Even though Zutto Kimi no Turn was printed as a complete book later, the main events of its story take place before and during the events of Memeshii Aku. Option B: The Publication Order (How the Author Released It) If u care about following the original release timeline..read Memeshii Aku to Azatoi Suu first.
UNIVERSE 2: The "Heartbeat" Series This is a newer series by Takuma with a different set of characters and share the same world. Asuma (the main character of Unmatching Heartbeat) actually appears as a background character in Universe 1 before getting his own story.
2)Abnormal Heartbeat (Side Story) A direct side story that takes place after the events of Unmatching Heartbeat. It deals with their relationship at a "more romantic stage," though Asuma faces some new hesitations. https://www.mangago.me/read-manga/abnormal_heartbeat/ Oneshot (Complete)
(Universe 2 Extended) AUTHOR Takuma has actually expanded Universe 2 significantly since then,Newer sequels that follow Keigo and Asuma: Heartbeat Flagged: A direct sequel continuing their relationship drama. Shinsing Heartbeat: Another continuation chapter. Unmatching Heartbeat HYPER (2026): The brand new, major serialized sequel volume that continues their adult life together.
Note on extra content: This specific HYPER volume compiles the individual side chapters you listed (Abnormal Heartbeat, Heartbeat Flagged, Shinsing Heartbeat, and the Unmatching Heartbeat Prototype SNS illustrations) into a single cohesive collection.
Notes: Just sharing information found on MangaUpdates & the Japanese version of RENTA I am also waiting for the uploader to update the upcoming volumes and chapters. Apologies in advance if any details are incorrect!
RELATED SERIES TIMELINE
UNIVERSE 1: The "Always Your Turn" Series
1)Memeshii Akuto Azatoi Suh / Whimpery Aku and Impish Su (Adapted From) 2018
https://www.mangago.me/read-manga/memeshii_aku_to_azatoi_suh/
1 Volume (Complete)
2)Zutto Kimi no Turn/It’s Always Your Turn (Spin-Off)2019
https://www.mangago.me/read-manga/zutto_kimi_no_turn/
1 Volume (Complete)
You can actually read them in two different ways depending on your preference
Option A: The In-Universe Chronological Order
If u care about character backstory etc..read Zutto Kimi no Turn first.Even though Zutto Kimi no Turn was printed as a complete book later, the main events of its story take place before and during the events of Memeshii Aku.
Option B: The Publication Order (How the Author Released It)
If u care about following the original release timeline..read Memeshii Aku to Azatoi Suu first.
3)Ore no Kareshi ga Konna ni Kawaii / My Boyfriend Is Seriously Cute (Side Story)
https://www.mangago.me/read-manga/my_boyfriend_is_seriously_cute/
included inside Zutto Kimi no Turn UNDER : CHP 8.6
Oneshot (Complete)
4)Kono Otaku, Couple ni Tsuki /This Otaku Couple (side story)
https://www.mangago.me/read-manga/these_two_otaku_are_a_couple/
Oneshot (Complete)
5)Doujinshi Mitai na Koto Shiyou! /Let's Do Something Like a Doujinshi!(Side Story)
https://www.mangago.me/read-manga/zutto_kimi_no_turn/uu/br_chapter-132541/pg-1/
included inside Zutto Kimi no Turn UNDER : EXTRA chp
UNIVERSE 2: The "Heartbeat" Series
This is a newer series by Takuma with a different set of characters and share the same world. Asuma (the main character of Unmatching Heartbeat) actually appears as a background character in Universe 1 before getting his own story.
1)Unmatching Heartbeat (Spin-Off)(Main Story)
The primary story of childhood friends Keigo and Asuma.
https://www.mangago.me/read-manga/unmatching_heartbeat/
1 Volume (Complete)
2)Abnormal Heartbeat (Side Story)
A direct side story that takes place after the events of Unmatching Heartbeat. It deals with their relationship at a "more romantic stage," though Asuma faces some new hesitations.
https://www.mangago.me/read-manga/abnormal_heartbeat/
Oneshot (Complete)
(Universe 2 Extended)
AUTHOR Takuma has actually expanded Universe 2 significantly since then,Newer sequels that follow Keigo and Asuma:
Heartbeat Flagged: A direct sequel continuing their relationship drama.
Shinsing Heartbeat: Another continuation chapter.
Unmatching Heartbeat HYPER (2026): The brand new, major serialized sequel volume that continues their adult life together.
Note on extra content: This specific HYPER volume compiles the individual side chapters you listed (Abnormal Heartbeat, Heartbeat Flagged, Shinsing Heartbeat, and the Unmatching Heartbeat Prototype SNS illustrations) into a single cohesive collection.
Notes: Just sharing information found on MangaUpdates & the Japanese version of RENTA I am also waiting for the uploader to update the upcoming volumes and chapters. Apologies in advance if any details are incorrect!