Jungkook of boy band BTS will start his military duty next month, the singer announced in a letter to fans on Weverse on Wednesday.

"I am beginning a new journey in December and will be temporarily leaving your side to fulfill my military duty," Jungkook wrote on fan community platform Weverse.

"A part of my heart feels heavy to share this news, while another part of my heart warms to think back on the precious memories I had with ARMY," he added, mentioning the band's official fan club ARMY by the name.

"Every moment of life that I shared with you had been the brightest moment of my life. ARMY's laughter, support and love have led me here to where I am now. Thank you so much for taking this road with me."

Earlier on Wednesday, BTS's agency BigHit Music announced that four members of the band — Jungkook, RM, V and Jimin — began the procedure to fulfill their military duties, following the footsteps of three members Jin, J-Hope and Suga, who already started their duties.

"I do feel cautious about asking you to wait while I serve," Jungkook said. "A year and six months is a long time, so I will not say anything selfish, but I only promise you that I will take the stage again when I'm back — where I always was, but grown up even more."

"I will miss you in the deepest of my hearts until the day we meet again and share our stories," he added. "Stay healthy and stay safe. I love you."

BY YOON SO-YEON [yoon.soyeon@joongang.co.kr]