BOSTON -- Cubs president of baseball operations Jed Hoyer walked into his office on Thursday and found a book that another front-office member had left on his desk. It was a book on pitching that lefty Shota Imanaga published last year in Japan, offering mental and physical guidance for younger pitchers.

“I can’t read it, obviously,” Hoyer said with a laugh on Friday, sitting in the visitors’ dugout at Fenway Park. “But it just shows you that’s what he’s like. He’s very thoughtful. Obviously, he has the nickname of ‘The Pitching Philosopher.’”

Imanaga has been putting his philosophies on display in his first month in the Majors, performing as one of the Majors' top arms in the season’s early going. In the Cubs' 7-1 victory at Fenway Park, the lefty kept it going against the Red Sox, one of the teams vying for his services over the winter.

Imanaga pitched into the seventh, improved to 4-0 through his first five starts for Chicago and headed off the hill with a 0.98 ERA. The lefty struck out seven and issued one walk, upping his ratio to 28 strikeouts against just three walks in 27 2/3 innings on the year.

As a result, Imanaga became the first Cubs starter to go at least 4-0 through the first five games of his career, and only the 37th pitcher to do so in AL/NL history. He is the first starter since 1945 (Boston’s Dave Ferriss) to go at least 4-0 with an ERA below 1.00 in his first five career games.

“It’s a lot harder to build trust than to break it,” Imanaga said via his interpreter, Edwin Stanberry. “The fact that my teammates are trusting me and I’ve been able to build that up, I’m really glad.”

Over a career-high 6 1/3 innings, Imanaga limited Boston to one run via a rocket shot to center field off the bat of Tyler O’Neill in the fourth. As Chicago’s starter watched the ball carry out, he leaned back and wore a momentary look of shock. Imanaga then turned around, nodding his head as he continued on with his outing.

“The fact that he hit it to dead center, I was pretty surprised,” Imanaga said. “The most important thing is to switch my mindset, adjust and then keep going. I was able to do that.”

That evaluation fits with the way people around the pitcher speak about his personality.

"One of Shota’s best traits is that he’s very curious. He’s very open,” Cubs manager Craig Counsell said before the game. “He takes in information very well. I think he watches very well. And that leads to someone who’s very good at making adjustments.”

That mentality on Imanaga’s part helped play a role in the Cubs’ recruiting of the lefty before he signed a four-year, $53 million pact with the team in January.

Imanaga was interested in how Chicago’s pitching group felt they could utilize his repertoire against Major League hitters. He swiftly put some of the ideas -- one being attacking the upper part of the zone more with his fastball -- into practice during Spring Training. That helped build a foundation for the season.

Imanaga featured five pitches against the Red Sox, leading the way with his four-seamer (40 pitches) and splitter (33). He generated 14 swings and misses and escaped the handful of jams he faced. That included striking out Pablo Reyes to end the sixth, stranding two runners. Imanaga howled in celebration as he bounced off the mound.

“He’s doing the things that we envisioned [when we tried to recruit him],” Red Sox manager Alex Cora said. “I think what [the Cubs] are doing is pretty similar to the plan that we had. It’s a good fastball. We were talking about it today.”

Imanaga also helped his cause in the field.

In the first inning, Red Sox leadoff man Jarren Duran sent a soft liner back up the middle, but Imanaga made a quick, stabbing catch. In the fourth, Duran bunted a ball to the first-base side of the mound. Imanaga hustled over, plucked the baseball from the grass and used his glove to flip it to first for another out.

“He made some really nice plays,” Counsell said.

The more Imanaga pitches, the more the book will be out on the lefty.

“He’s going to evolve,” Hoyer said. “He’ll figure out people will see him, and he’ll have to make adjustments. But the way he is as a person, I don’t have any doubt that he’ll make those adjustments well.”

As for the book on Hoyer’s desk?

“It’s going to take a while to read that book,” Imanaga quipped. “I’m going to have Edwin help him out.”