Yeah so here's the translation from the point of Mina explaining her motives, if something there isn't clear I'll make sure to answer any questions
Mina's motives:
Renachii's bright future, Yuko's big breasts, Mayuyu’s idol personality,and Takamina's leadership. They're all stealing/copying my character.
Dead members & Takamina:
We're not copying you!
Acchan's explanation:
Minegishi appeared in all other CMs so I had her act as a helper. Now, the mesages left on the victim's mobiles and the song playing from them. Sakkiko told me that the song is "Mozart's 18th piano sonata" and AKB's 18th single was "Beginner".
Kojima in flashback:
Being a detective is impossible for a "beginner"
Acchan cont:
And I'm also a beginner detective but that doesn't matter since the songs on the phones all suddenly stop at different points. If you play the song up to that point the last line before it would stop would be this, from Renachii's phone "Become 0" (0 になるんだ) Yuko was frozen to death (0 degrees). Yuko's phone "To stab" (さすよ)Mayu was stabbed. Mayu's phone "Controlling chains" (支配された鎖)Takamina was almost strangled by a chain. They were all explaining how the next victim would be killed.
Now, the codes on the phones. The numbers mean the "number of lines" and the alphabet letters mean the "order of letters". If you look at the lyrics from the "Beginner" single and match up the codes, 23rd line K(11th) letter is "こ" and 24th line AB(1st & 2nd) letters are "リス". They join together to form "コリス" (korisu), one of Yuko's nickname. If you do the same with the next code 16th line A(1st) letter is "C" and 33rd line K(11th) letter is "G", this forms "CG" one of Mayu's nickname. Finally the 47th line H~M (8 to 13th) letters spell out "REBORN" which can be pronounced as "RIBON",one of Takamina's trademarks.
Mina:
Impressive but how did you know I was the murderer?
Acchan:
The victims told me. Firstly Renachii and the letter "N" she left behind. This wasn't "N" but in fact "IV" which meant 4 in roman numeral. Also there was another thing strange with the letter, it was written using her thumb as if leaving a "thumbprint" (thumbprint in Japanese is called a BOIN/ぼいん). Next is Yuko, she is also showing a 4 with her fingers and holding her breasts, as if to show a "BOIN/ボインー" ( the sound made in anime/manga when breasts are bouncing) Finally Mayu left a message on the keyboard where you take out the 4 and use the rest of the letters to form the word "VOWEL". Vowel in Japanese being "BOIN/ぼいん". This means the victims dying message all meant "4 VOWEL". Within all mebers of AKB only 2 mebers fit this the deceased KATO RENA and OBA MINA, it can only be you.
Mina:
Sorry, can you explain again?
Mina:
This means my life as an idol is now over
Acchan:
Baarou~ This episode was all just fictional.