There is a lot of information on the perception of how the Ming & Joseon felt toward the Japanese, but not a lot of information on how the Japanese felt towards the Joseon and Ming armies compared to Admiral Yi.
Were the Japanese surprised at the speed they were able to take Korea? Did they expect more pressure from the Korean army? For example; during the battle of Chongju, one Japanese contingent sat aside believing his rival might need assistance against the Koreans, instead he easily defeated the army without much loss.
I understand Hideyoshi himself believed he was going to not only take Joseon, but also the Ming as well and rule from Beijing. But how did his Generals and soldiers feel? What were their impressions of the Joseon and Ming?
How did they feel about the Guerilla warfare tactics of the remaining the Korean army? What were their impressions when the Ming arrived? We know the Ming were still over-confident toward the Japanese, but later on were more careful upon realizing they were a real threat.
Did the Japanese believe they were going to just as easily defeat the Ming army? Did impressions change after the allies retook Pyongyang? And did it change again after the Ming failed to push further and drew a stalemate?
In the wiki, "Li Rusong is often disparaged in Japanese accounts" but not a lot of information in what ways.
Follow up question is what were their impressions of each other in terms of their performance on land?
Any eye opening information would be awesome!
According to Luís Fróis (a Portuguese Jesuit residing in Japan and friend with Oda Nobunaga. He was the author of "Historia de Japam/History of Japan"), Konishi Yukinaga looked down on Chinese troops, but quickly learned to respect their prowess after their first contact (i.e. first Ming attack on Pyongyang, in which 3,000 Ming cavalry were lured into Pyongyang and ambushed, losing some 300~1,000 men. Despite losing the battle, Chinese soldiers left a deep impression on Konishi).
After Battle of Byeokjegwan (Ming lost this battle too), fear of Ming army began to run deep. Luís cited the fear as one of the reasons Japanese sued for ceasefire/negotiation.
EDIT
Obviously, Luís was in Macau at the beginning of Imjin War, and did not personally witness what he wrote (it should be noted that given his relatively good standing with the Japanese, he did have good access to information, and could give a less-biased outsider POV).
However, his opinion can be corroborated with Korean and Japanese accounts. According to Annals of King Seonjo, Japanese soldiers inside Pyongyang stopped coming out of the city to pillage the countryside for a few days out of fear that Ming army might return, and even complained to the Koreans that Ming soldiers they just fought were completely unlike the weaklings they imagined.
For Japanese source, Seikanroku, a primary document of Shimazu clan, also records that after Byeokjegwan, Kato Kiyomasa and Asano Nagamasa refused to follow order from Hideyoshi himself to attack Jinju out of fear that Li Rusong might come back to attack them. They instead proposed to build a fortress between Kaesong and Jinju, and let Shimazu Yoshihiro garrison it against potential Ming attack (which Shimazu also cleverly refused). It was not until Hideyoshi issued another order (he asked Shimazu to join with the rest to attack Jinju) that they complied.
By the second phase of the war, the fear was such that news of a coming major offensive of one million Ming soldiers (later turns out to be a bluff from a captured Ming scout) scared Shimazu Yoshihiro into abandoning his position in Jinju and retreat to Sacheon. Konisi Yukinaga almost did the same with Suncheon too, but was persuaded against the idea by his subordinates. The same fake news also caused Ukita Hideie, Mori Hidemoto, and a dozen of other commanders to directly petition Hideyoshi, asking for his permission to abandon Ulsan, Suncheon and Yangshan, as they thought those places were too vulnerable (Hideyoshi angrily declined their request).