Reigen Arataka in the manga and anime is mostly similar. However, in the anime, maybe the color palette and animation style give a slightly different impression of his character. Also, the voice acting can add a new layer to how we perceive him compared to the static images in the manga.
There are some differences. In the manga, Reigen's expressions might be more detailed, while in the anime, his actions could be emphasized more.
Overall, the Reigen Arataka character maintains his core traits in both manga and anime. But in the anime, there could be more visual effects to enhance his personality. Some of his dialogues might also be delivered differently for better audio impact.
Chapter 118 is the strongest chapter-level answer because it starts from At 8 in the morning, several guests appeared on time next to the... and follows through on Hearing this, both Jiang Yan and Shu Yan started to complain as well..
If you want the clearest chapter reference, go to Chapter 149. Early on, Seeing that Zhang Cheng's glass was nearly empty, Du Qinglian immediately...; later, the chapter leans on Director Zhang, this Zuichun Mountain is a specialty of Bi Garden, brewed....
The best chapter pointer here is Chapter 134, "Being able to accompany Miss Jiang is my good fortune". It opens with After a brief noon rest, the production team was up to their antics again. and closes on [Are you kidding me, is Jiang Li putting on an act again?.
Look to Chapter 136 for the clearest answer. It begins with A few people retraced their steps back to the place they had just been., keeps building through They continued straight up the mountain path until the trees became denser..., and lands on Aunt Ying and the camera PD arrived soon after..
The best chapter pointer here is Chapter 121, "Jiang Li Gains 5 Points for His Meritorious Rescue!". It opens with Seeing that Wen Jiaojiao's condition had improved significantly, Director... and closes on You're supposed to be a man who conquers mountains!] Experienced and....
Look to Chapter 128 for the clearest answer. It begins with Still hungover, Huo Ziyang had just awakened from a blurry dream when his..., keeps building through He clicked his tongue in annoyance and picked up the phone., and lands on There had been no shortage of Weibo posts criticizing Jiang Li.
Chapter 121 is the strongest chapter-level answer because it starts from Seeing that Wen Jiaojiao's condition had improved significantly, Director... and follows through on You're supposed to be a man who conquers mountains!] Experienced and....
The best chapter pointer here is Chapter 127, "He's Not Snobbish, Just Simply Bad-Tempered". It opens with Witnessing Jiang Li leave with a bucket, Jiang Yan refused to admit... and closes on He Yun, who chose the codonopsis, became the one with the most challenging....
A practical answer is Chapter 127, because it turns the idea into a concrete scene. The chapter opens with Witnessing Jiang Li leave with a bucket, Jiang Yan refused to admit..., adds pressure through [LOL, I'm dying laughing, the Young Master is cursing heaven and earth..., and ends on He Yun.