Demo, ore wa Shinjō ja nai ka to yosō shite iru n dakedo
But I'm guessing it might be Shinjo.
The "to" particle after "Shinjō ja nai ka" is like a verbal quotation mark, right? Except it's marking a thought in this case rather than a spoken opinion.
""Shinjo, isn't it?" [I'm] guessing."
Demo, Mizunuma-san ga jōshi ni natte mo, Shinjō wa nattoku shinai n ja nai kana.
But even if Mr. Mizunuma becomes the assistant manager, I don't think Shinjo's going to agree with it.
Double negative here - "Shinjō wa nattoku shinai n ja nai kana"
"Shinjo, won't fully understand, will he? I wonder..."
Nōryoku ga aru noni, mitomete moraenai kaisha nante yameru! tte iu kamo shirenai zo
He might just say "I'm not staying with a company that's not going to recognize my skills and talents!"
"Nōryoku ga aru noni" = To have the ability in spite of...
"mitomete moraenai" - not recognising [for someone else - in this case, other people not recognising his talents]
"kaisha nante yameru!" - company [I'm going to] quit! - with "nante" just for emphasis, right?
"tte iu" - "tte" being like a verbal quotation mark then "iu" meaning "to say."
Demo, sainenshō no Shinjō ga jōshi ni natte mo, umaku minna o matomete ikenai ki ga suru zo.
But even if Shinjo, the youngest of them all, becomes assistant manager, I feel like he won't be able to organize everyone
"umaku minna o matomete" - skillfully, everybody, put in order - the word order is difficult, why isn't the adverb "skillfully" in front of the verb? Here it's in front of "everybody." "Skillfully" is describing the way the verb happens, it's not modifying "everybody."
And I don't know why the object marking particle "o" is used rather than the directional particle "ni." I've noticed that in other cases too, like "Natsuko-san o yobu" (to call Natsuko). What is the rule for using "o" instead of "ni" when it would seem more logical to use "ni"?
"ikenai" - "don't do"
"ki" - "skill"
"ikenai ki" - "doesn't have the skill?"
"suru" - why isn't this in the potential form, "dekiru?" They're talking about an expression of ability.