The 54-year-old suspect, identified as Cao Jianping, was taken into custody shortly after the shooting in the capital's Ikebukuro neighbourhood yesterday.
Security footage reportedly showed the pair embroiled in quarrel shortly before the shooting, a rarity in Japan where crime involving firearms is usually connected to yakuza organised crime groups.
A spokeswoman for the Tokyo Metropolitan Police today confirmed that a Chinese national in her fifties was fatally shot in her chest.