Nice!

Yikes. It didn't really come across to me in the other parts of this mission, but that Takara really was quite a villain protagonist, huh? Funny a character can be so awful, but still be focused on by the narrative as the "hero." I think the fist fight finale was appropriate, and you did well to rely on a canon character to deal the final blow, rather than the agents. If nothing else, Otegine deserved a little catharsis after how badly Takara maligned it!

It seems I was only partly correct about Ishitani. I had guessed he was actually Kaguya, but I thought all the time travel shenanigans in the fic had caused him to get stuck in the universe for a while and age up, and that he then used the RA to portal back to Momoka during the mission. But I like the truth better; I've never really liked the existence of the D.O.R.K.S., as I feel like it makes things too easy for agents in the field. But this was probably the best narrative use of a D.O.R.K.S. I've yet read in a mission!

Some grammar notes:
"Takara married Hajime on February 1945 . . ."
This should be "in February." (If there were a specific date there, then "on" would be correct: "Takara married Hajime on the 28th of February, 1945.")

". . . and all and all being the worst, most tyrannical . . ."
This might vary by regional dialect, but I usually see this phrase as "all in all?"

"Unfortunately, both her knives went flying out of her hands and herself was thrown to the ground."
Since "both her knives" is the subject of the first clause in this sentence, the second clause needs a new subject. This can either be ". . . and she was thrown to the ground" or ". . . and she herself was thrown to the ground."

"'. . . then take both and Otegine to FicPsych for therapy.'"
Either the two bolded words shouldn't be there, or the name of another character is missing.

—doctorlit sticks all the way through multi-parters, always!