Does this series have any connection to other works by Yuto Suzuki?

The series originated from a 2019 one-shot manga titled Garaku, which featured a different protagonist and served as the conceptual foundation for the world and tone later developed in this series.

Is this manga part of a larger shared universe or does it stand alone?

While the story is a self-contained narrative, it exists within a broader media franchise that includes a light novel titled Sakamoto Days: Assassin's Method and a spin-off manga series titled Sakamoto Holidays.

Sakamoto Days, Vol. 4

Manga Crime

Pages: 200
Published: 2021
Language: English

Synopsis

Taro Sakamoto was once a legendary hit man considered the greatest of all time. Bad guys feared him! Assassins revered him! But then one day he quit, got married, and had a baby. He's now living the quiet life as the owner of a neighborhood store, but how long can Sakamoto enjoy his days of retirement before his past catches up to him?!

The race to rescue Lu takes Sakamoto and Shin deep into an underground lab. However, they're not the only ones there on a mission—the legendary members of the Order are there as well to investigate the mysterious X!