The new single lets the fans take a peek into what Jiwoo, who has already been a popular trainee among fans, had to go through to become Chuu; and her desire to be loved by Yves, who also has said in her lyrics "my heart that wants to be like you gets colored, filled with you". 

The title track Heart Attack does not interpret the feelings of being in love in a serious way, but with Chuu's adorable emoticon-like ways. The music video has reference to historical and fictional figures such as the artist Rene Magritte, Hans Christian Andersen's short story 'The Little Match Girl' and John Appleby's novel 'Aphrodite Means Death'. 

When four girls who denied the garden of Eden, the party begins. 

The above passage was Blockberry's description of Heart Attack by Chuu. There were a few interesting hints about Chuu and how she became a part of LOOΠΔ. 

(i) The mention of Yves' particular lyrics in her solo track new.  

My heart that wants to be like you

Gets colored, filled with you

I haven't noticed it before but there's a similar indication of colors in another two songs each by Haseul (Let Me In) and Chuu (Heart Attack) about how it consume them from within.  

The moon rises

And I'm becoming you

We were so different

But my heart is being colored with you

Dipped you inside my white heart

And made it red

Yves and Haseul have not mention any particular color whereas Chuu said 'she' or 'he' turned her heart red. Instead of her color, white symbolizes innocence and following Yves' rebellion turned it red. Red is associated with energy, war, danger, strength, power, determination as well as passion, desire and love; the very same color of the forbidden apple Yves ate (or rather took a bite). Chuu (as Jiwoo) has yet to follow Yves' footsteps as long as the apple stays green. 

Meanwhile, Haseul seeing the 'color' was said to be caused by rising of the moon (ODD EYE CIRCLE). 

On another note, mention of color(s) was also recited by other members' (Eclipse by Kim Lip, Singing in the Rain by Jinsoul, Love Cherry Motion by Choerry, ViViD by Heejin)   

I'm so excited because you have different color than mine

Will you show me the color which is hidden in your mind?

Hey baby

I'll see it under the light alone without anyone knowing

I'm going crazy because I'm curious 

The song of the night that grows deeper

Even I can't stop it, out of control

Even if I don't know where it started

It colors the night

I used to be untouchable and dangerous

But in just one moment your blue wraps around me

For the sin of swallowing up all the stars in the sky

You have spread blue

Following the sound, we're running, you and I (following)

The secret is getting deeper and deeper (falling)

The air is getting wet with the rain (coloring)

Hey the sun inside of us is getting colored now

I have fallen, love cherry motion

Into a purple, midsummer night's dream

Love cherry magic, dreaming of a paradise with you 

Every day, there's a flash in my heart

A shining rainbow

A colorless world is boring 

Will you change it with your fingers?

Red, orange, yellow, green, even thicker, be okay? 

Same color, say different color

So everyone goes crazy

Fill me with many colors, red, orange, yellow, green

Something highlight

Surprising changes

Only Kim Lip had not mention any