So the chp starts with us getting a glimpse of the past relationship between Sunbae and her Black haired senior.
Sunbae was going somewhere but the sudden rain side tracked her, there she suddenly saw her senior passing by and she then chased after her in the spur of moment only to realize it was someone else. This shows her lingering unkempt feelings for the senior, that at the slightest resemblance she chased after them instinctively.
At present, Sung-wa and her friends came together to hangout but to her suprise Sunbae is also here.(Sunbae is friends with their friend circle) When thing couldn't go more awkward for her, her friend has an emergency and leaves her at Sunbae's care.
Sunbae tires to indulge and make things less awkward by offering Sungwa to teach her how to play.
Under Sunbae's charming teaching gesture she realises that Jiyo would have obviously fallen for such gestures and disdains at Jiyo about this in her heart.
After the play both got somewhat comfortable and the atmosphere become ambient enough for them convers with each other. There firstly Sungwa noticed that Sunbae was slightly different from what she was expecting her to be. Sunbae then casually ask Sungwa to come hangout with her & Jiyo next time, at which Sungwa mentions that they had a fight and she can't. Sunbae ask her why, which was very ironic in Sungwa's pov, as everything about their fight has to do with Sunbae additionally she knows that Sunbae is also not totally clueless about the situation between her & Jiyo, as she has been teasing(mocking) her about Jiyo & herself every now and then.