2 January 2015, 13:16 GMT
Kim Yo-jong, 28, who is deputy director of the country’s ruling Workers' Party of Korea, accompanied the young leader on his field guidance to a tree nursery, which is being constructed by the Korean People's Army, Yonhap news agency reported Friday, citing the North's Korean Central News Agency (KCNA).
In April, South Korea's spy agency said that Kim would likely give birth in May, adding that her husband may be an alumnus of her alma mater, Kim Il-sung University.
Kim Yo-jong was last seen in public on April 12 when she accompanied her brother on his inspection of the construction site of a second airport terminal in Pyongyang, the Yonhap report said.
Both Kim Jong Un and his sister were born to Ko Yong-hui, the fourth wife of late leader Kim Jong-il.
