Having been captured by the elite guard Ellen is submitted to interrogation by Suzuka at their temporary command post. Meanwhile, Kaoru manages to rejoin Kanami and Hiyori with the intentions of taking them to their organization's headquarters, but without Ellen the girls press Kaoru for more information. Ellen takes advantage of her captivity to investigate the elite guard's secrets.
So this is the "human experimentation"
the letter mentioned.
.هذه "التجارب البشريّة" المذكورة بالرسالة إذًا
Darum ging’s in den Experimenten an Menschen,
die im Brief erwähnt wurden.
Estos son los experimentos
que mencionaba la carta.
Estos son los experimentos
que mencionaba la carta.
Ecco quindi a quali esperimenti sugli umani 
si riferiva la lettera.
Esse é o "experimento humano"
que a carta mencionou?
Про такие эксперименты
было написано в письме?