This is one of the most captivating stories I've come across in recent years.
I found it by pure chance in the "Random manga" display on the MangaDex start page less than 24 hours ago, and now I'm all caught up. My initial reaction was "guess this is another dumb gun/military otaku manga huh", reinforced by the fact that the artist, Nogami Takeshi, has drawn both Strike Witches and Girls und Panzer. But no, Marine Corps Yumi is actually a surprisingly accurate story about becoming a female US Marine, as told by its author, former US Marine Anastasia Moreno. Despite being a lighthearted comedy, it manages to convey strong emotions, and has a rather educational approach.
I was devastated to find out that the author, Anastasia Moreno, passed away from cancer in 2015. She handed over the remaining story to Nogami Takeshi before her death, who completed the manga with 7 volumes by late 2017. Moreno worked as a professional manga translator (she was eng/jap bilingual) after becoming a veteran, and did the excellent, official English version herself. Moreno's official English version only reached volume 3 chapter 78 before her passing, so now we'll have to rely on the scanlators to fill her boots for the remaining chapters!