Nature of the alliance between Japan and Germany in WW2

[PanzerJaeger]

I have never seen material to this effect, which doesn't mean it's nonexistent, of course. Could you perhaps provide examples?

All of my information comes from books I have read. I do not have time to readily cite specific communiqué.

Hoping that Japan would feel obligated is far different than 'courted...for nearly a year'.

Indeed it is. That is because you are referencing two different events. Hitler courted the Japanese before the invasion without success. After the attack on Pearl Harbor, he again saw an opportunity to get Japan into the war against the Soviet Union, which was especially important considering the failure to take Moscow.

I'd also be curious why Hitler would feel the need for Japanese participation given that in the original planning for Barbarossa the campaign was to be concluded within six months.....

Despite his reputation, Hitler always sought Allies, regardless of whether he felt he could win on his own or not.

Edit:

I did some searching for sources, and there is a wikipedia page specifically dedicated to the issue we’re discussing, which would have been helpful earlier. It seems well sourced and comprehensive. It provides some of the communiqué you requested, and supports my general assertions.

Specifically,

In order to directly or indirectly support his imminent invasion of the Soviet Union, Hitler had repeatedly suggested Japan to reconsider plans for an attack on the Soviet far east throughout 1940 and 1941. In talks involving Hitler, his foreign minister Joachim von Ribbentrop, his Japanese counterpart at that time, Yōsuke Matsuoka, as well as Berlin's and Tokyo's respective ambassadors, Eugen Ott and Hiroshi Ōshima, the German side broadly hinted at, but never openly asked for, either invading the Soviet Union from the east or by attacking Britain's colonies in South-East Asia, thereby preoccupying and diverting the British Empire away from Europe and thus somewhat covering Germany's back.[28] Although Germany would have clearly favored Japan attacking the USSR, exchanges between the two allies were always kept overly formal and indirect, as it is shown in the followng statement by Hitler towards ambassador Ōshima from 2 June 1941:

"It would, of course, be up to Japan to act as it saw fit, but Japan's cooperation in the fight against the Soviet Union would be welcomed if the [Japanese] advance to the south should run into difficulty because of supply and equipment."

Also,

Hitler chose to declare war on the United States and ordered the Reichstag, along with Italy, to do so on December 11, 1941, three days after the United States' declaration of war on the Empire of Japan. His hopes that, despite the previous rejections, Japan would reciprocally attack the Soviet Union after all did not transpire, however, since Japan sticked to its Nanshin strategy of going south, not north, and would continue to maintain an uneasy peace with the Soviet Union until 1945.