The 41-year-old Japanese man who shot Mr Abe told investigators he had been “dissatisfied” with Mr Abe and had wanted to kill him.
Mr Buhari said Mr Abe will be remembered for his unwavering commitment to strengthening trade and investment between Africa and Japan.
Russia is suspending an agreement that allows Japanese fishing companies to harvest in waters near the disputed Kuril Islands.
Top EU officials will be in Tokyo on Thursday to meet Prime Minister Fumio Kishida, in hopes of deepening ties with Japan, a strategic ally and neighbour to both Russia and China.
The suspect said he regrets that nobody died in the attack. He said he had been thinking of the death penalty since June.
A powerful earthquake that struck Tokyo on Thursday disrupted train services on Friday morning, affecting around 368,000 passengers.
Musa Nimrod was re-elected on Thursday after polling 11 votes out of 14 registered voters.
A record 4,403 athletes are competing at the Tokyo Paralympic Games, which began on Tuesday night, International Paralympic Committee
The AFN said several attempts made to deliver the PUMA kits to the athletes in Tokyo, were frustrated by the youth and sports minister.
There have been nine positive cases among those linked to the Games on Tuesday, taking the overall number of people infected since the start of July to 71.
