Ito's fine strike in the 79th minute gave Reims a win which leaves the club from Champagne country, around 150 kilometres north-east of Paris, just four points adrift of the European qualifying places.
His goal, his third of the season, came just three days after the winger was left out of the Japan squad for home and away World Cup qualifiers against North Korea later this month.
Ito left the Asian Cup last month after Japanese police said he was under investigation over an alleged sexual assault in Osaka last year.
Still said Ito, formerly of Belgian side Genk as well as Kashiwa Reysol, had been "mentally strong and faithful to himself".
"He hasn't doubted himself or let himself get too down," Still added of Ito, who has started each of his side's last six Ligue 1 games.
"I take into consideration the human being when he is at the club.
"We have been there for him. He has been there for us.
"He is a key player, undoubtedly one of the best Japanese players at the moment.
"We need our important players to win us matches sometimes, if we are not able to do so collectively."
Ito denies the allegation against him and is suing his accusers for 200 million yen (£1.05m) in damages.
Japan coach Hajime Moriyasu said he had not called Ito up to his latest squad as he felt it would be difficult for the player to focus on football if he returned to the country at the moment.
"I tried to imagine what the surrounding environment would have been like for him in Japan and I didn't think it would be one that would allow him to live and play football in peace," local media reported Moriyasu as saying.
"It wasn't just him - I didn't think the whole team would have been able to go about their business in peace."
