So I had a late start to this show, which is about a specialized group of Japanese international spies before World War II started. I noticed that every time there's a show about Japan and militarized warfare, many people like to pounce on it for their war crimes during World War II. It's hard to avoid this discussion while it's still being heavily politicized in Asia. In any case, it happened with this show as well.
In episode 3, there's this moment when the French-speaking spy has a discussion with the spymaster, who is surprised that Imperial Japan is allying with Germany. Many fans garnered from that that the show is engaging in whitewashing Japanese sentiment. The actual history of the pre-war events is quite fascinating and puts things in perspective. I recommend people to read further up on it, but I'll quote this comprehensive summation of the topic, to keep it relatively short. I've edited in a few words as well.
Prior to 1940 nearly the entire leadership of the Imperial Japanese Navy opposed all-too-close ties with Germany. Prior to 1939-40 the main proponent of a Japanese-German alliance was the Imperial Japanese Army with their Northern Strategy aimed at the Soviet Union, and their war in China. The IJN with their Southern Strategy [note: planned expansion over South-Eastern Asia] was fundamentally opposed to conflict with the Soviet Union and high-ranking IJN leaders were extremely critical of the IJA's expansion of the war in China. As such Japanese-German relations took a blow when Germany, ignoring the provisions of the Anti-Comintern Pact of 1937, agreed to a pact with the Soviet Union. Negotiations to expand the relations into an alliance during that time also ran into a dead-end since Germany wanted to direct the pact against the United States and Britain, which other than army minister Itagaki Seishiro, just about every cabinet member, as well as the leadership of the IJN refused.
The situation began to change in 1940 when Germany overran Western Europe. With the weakness of the European colonial powers and seemingly good German-Soviet relations to army started favouring southern expansion. Thus negotiations towards a Tripartite Pact were restarted, the cabinet of Prime Minister Yonai who opposed an alliance with Germany on principle ousted, but now with an entirely different target. The aim of the alliance was deterrence against the United States. The main drivers on Japanese side hoped to expand the Tripartite Pact to include the Soviet Union to keep the US in check and give Japan free hand in Southeast Asia. To one of the main proponents of the Tripartite Pact, foreign minister Matsuoka Yōsuke, alliance with Germany was all but a tool to achieve alliance with the Soviet Union. China was completely irrelevant to the decision. With this change in focus IJN resistance waned and the Tripartite Pact was concluded in September 1940.
The episode in France is set before September 1940, so the alliance was still in doubt. While the momentum moved towards the Tripartite Pact significant hurdles still existed, including opposition by high-ranking Japanese officials / officers who possessed good knowledge on the capabilities of the United States. These people correctly assessed that the alliance wouldn't keep Japan out of a war with the United States, but rather worsen the relations of Japan and the US. Assuming Hatano to be a knowledgeable man with a realistic view on the world it is not implausible at all that he would find the idea of Japan binding itself to Germany shocking. Moreover, Hatano had been in France for some time. It's pretty unlikely that he was on top of things regarding the latest domestic development in Japan.
tl;dr There is precedence for Hatano's surprise after hearing Japan was allying with Germany. Surely, Imperial Japan had targets in China and Russia at the time, but the sentiment of regular people, as well as that of high leadership positions, wasn't anywhere near as extreme as Germany's. They were also expressly anti-anti-Semitic and offered refuge to many Jews after fleeing from Germany.
Anyway, just found it interesting how we tend to view Japan in historic context as a foolish nation which allied with Nazi Germany, while the internal conflict to do that was all over the place.