ViVi and Yeojin, thanks to them, LOOΠΔ 1/3 is completed. ViVi was seen as a human in Everyday I Love You and Everyday I Need You but in Love and Live and You and Me Together she became an (expressionless) android. 

ViVi, when she was still human, it's the time where ODD EYE CIRCLE world is in black and white. Jinsoul briefly appears in Hong Kong (Everyday I Need You) probably looking for missing Choerry. 

At this time, Yves (D-1) also learned about ViVi's travel to LOOΠΔ 1/3 world (Love & Live). 

What do I do?

I spend my days with a frustrating heart

A bridge decorated with a rainbow of twinkling stars

Hold on to us, don't miss it, let go

For now I'll just take one step closer, closely, slowly

How you like me? Will you tell me now? 

ViVi's travel is out of curiosity (why/how the mirror cracks) and given she filled in for Yeojin, leaving the spot unoccupied risks Yeojin losing her place in LOOΠΔ 1/3. To prevent Yves from coming over to LOOΠΔ 1/3 and protecting Yeojin's spot, she plans to give chocolate to Yves just in case (Valentine Girl). 

I was determined as I gave you chocolates in February

February was declared as Yves' original month (December was for Haseul). 

Not wanting to be found by Yves or Jinsoul (since their mirrors are close by), ViVi sent an android of herself as a diversion. The girls' memories are stored in casette tapes and their previous self are trapped in the 90s. Only ViVi's memory remain with her, which is why her casette tape case cracked thus Yves will come to a dead end.

With a limited time, (android) ViVi carries out her mission which is keeping an eye on Hyunjin, Haseul and Heejin until their memories return. The girls, unaware of the whole thing, readily accepts (android) ViVi into the group. They think she is a lost android who is trying out what being a human means. In return, they showed her meaning of friendship and care for her. 

However, they eventually discover ViVi's identity and Heejin's hidden secret (Sonatine) through Hyunjin.

When the hidden secret is about to be revealed

Blockberry Creative described Sonatine is filled with pain and worries in the process of love, in the opposite characteristics of Love & Live. 

The intro track Love & Evil produced by SWEETCH materialized a girl who is lost alone in a dark forest. With the piano played in Accelerando, the girl runs away deeper into the forest. 

Four girls then gather to sing a Sonatine to cast an arcane spell of love.

The girls who are lost in the forest have gathered here. Can they save Yeojin? 

Based on these descriptions, ViVi (android or human) must