The penultimate episode of the blockbuster hit series finally graced the screen! In "Twenty Five, Twenty One" episode 15, things get more complicated for Kim Tae Ri and Nam Joo Hyuk as time and proximity test the strength of their relationship.

Keep on reading to know what went down in the latest episode!

'Twenty Five, Twenty One' Episode 15: Baek Yi Jin, Na Hee Do Turn 25, 21

In "Twenty Five, Twenty One" episode 15, the Tae Yang High School squad develop and grow together as they become one step closer to their dreams.

Go Yu Rim (WJSN Bona) migrates to Russia, and goes by the name Go Julia to represent the country in competitions.

Moon Ji Woong (Choi Hyun Wook) still tries to figure out his life and Ji Seung Wan (Lee Joo Myung) finally enters university as a freshman.

Na Hee Do (Kim Tae Ri) works hard in training to make South Korea proud. Baek Yi Jin (Nam Joo Hyuk) transfers to the local news department and thrives as a news reporter.

Yi Jin and Hee Do, despite their busy schedules, make things work and vow to love one another forever. The two welcome the year 2001 as 25-year-old Yi Jin and 21-year-old Hee Do who are filled with hopes, dreams and love.

Na Hee Do, Go Yu Rim in Madrid 2001

Before Hee Do and Yu Rim reunite in Madrid, Spain, the latter stopped returning Hee Do's emails, completely detaching herself from her old friend.

During the competition in Madrid, the former teammates once again face each other as opponents. It was a crucial competition as prying eyes darted their gazes on the fencing match.

Hee Do, who represents South Korea, defeats Russian fencer Yu Rim by a point.

Even when the people twist their words to pit them against each other, Hee Do and Yu Rim embrace one another after their match.

Yu Rim apologizes for not reading the former's emails but Hee Do just tightens the hug, saying she understands her completely.

The two express their honest feelings with tears streaming down their faces.

Baek Yi Jin Starts To Draw Distance

To celebrate Hee Do's success in bagging the gold medal, Hee Do's mother, who is also Yi Jin's senior at work, invites him to a celebratory dinner.

Unfortunately, Yi Jin couldn't make it due to the nature of his job. Yi Jin tries to pacify an upset Hee Do with a surprise couple trip.

However, the bombing in the United States happened. The local news department of UBS sent Yi Jin to New York, completely ghosting Hee Do and their couple's trip.

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Yi Jin experiences the hell of the aftermath of the bombing in New York as he interviews survivors, watch building crumble in smoke and witness people die day by day.

Because of this, Yi Jin starts to have nightmares. Hee Do, who worries about him, satiates her longing with Yi Jin's face on the news.

Na Hee Do Celebrates the New Year Alone

Yi Jin once promised Hee Do that he'll be back in South Korea before the year 2001 ends.

However, Hee Do welcomes the year 2002 alone. Hee Do's mother then breaks the news that Yi Jin applied as a local news reporter in New York.

READ MORE: 'Twenty Five, Twenty One' Episode 14: WJSN Bona 'Betrays' South Korea, Nam Joo Hyuk Congratulates Kim Tae Ri For THIS

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Written by Elijah Mully.