Regional and multilateral issues are likely to be discussed by the two leaders.Modi will also meet host-nation premier Thongloun Sisoulith, South Korean president Park Geun-hye and Myanmar's State Counsellor Aung Sang Suu Kyi.
Modi held extensive bilateral meeting with his Japanese counterpart Shinzo Abe on Wednesday.
India and Japan pledged to further strengthen cooperation in the area of counter terrorism, trade and investments.
He also conveyed his condolences to Abe for the Japanese lives lost in the recent terror attack in Bangladesh in which 22 people were killed after Islamist militants stormed a cafe popular with foreigners.
Abe said Japan was not going to succumb to terrorism and expressed the desire to further strengthen cooperation with India in the area of counter terrorism.A gala lunch will be hosted by the Laotian premier. Modi leaves for New Delhi in the evening.