Miyaichi is already flying for the Trotters since his January arrival.
Coyle said: "He went to Millwall and scored a wonder goal. He went to Chelsea and frightened the life out of their defenders and he did the same last week at Manchester City. Joe Hart had a wonder save from him.
"I am just excited by everything. He continues to grow, develop and I believe he will have a big impact in his remaining games.
"He's been fantastic since coming but he has to kick on."