I was directed to this list - http://dreamcast.onlineconsoles.com/php ... ist_jp.php
Dead or Alive does include an internet system, however, which would be almost an early variant of what appeared on Dead Or Alive Ultimate on the Xbox. You have a UPS (User Profile System) which is your name/username which stores your best times etc. This was expanded upon in Ultimate on the Xbox, as it also included online play.
There is also a Browser built into the game, which had a strange reaction with my VGA->HDMI upscaler, shifting the image of the game from it's usual centre to being too high and too far left (This resolution error stayed even after returning to the main game. Sod knows what it does, but turning the machine on and off should resolve it). This browser has a picture of Ayane in a bikini in the background, which is tiled on some menu screens, and has a few features set to Kanji text buttons assigned to the left and right triggers.
I know that early Japanese online systems are unable to be reproduced due to their dependency on old hardware-based networking protocols designed specifically around Japanese network architecture (Dwango), however Dead or Alive (Or Dead or Alive LE) was late to Japan, which is why it received a huge amount of additional content, so it's possible it didn't utilise the out of date system. I took this list from http://dreamcast.onlineconsoles.com/phpBB2/viewtopic.php?t=7284&sid=c294819fc749c80222ed8d2775855205
JP version of DOA2 has:
73 costumes, vs the US's 33
Bayman and Tengu as unlockable characters.
Extra breaks in "The Dragon Hills" stage
2 brand new stages: The Burai Zenin & The L's Castle
4 extra modes:
-Sparring (tag battle)
-UPS (User Profile System)
-Internet (webpage / rankings)
New dialogue differences
Tons more cutscene animations
Kasumi's default hairstyle is in a high ponytail instead of a low braid
CG Gallery Unlockables
I have yet to trial all of the features of the browser, it's possible many won't work without a true connection, however one allows you to erase content from the VMUs via a unique custom interface in the browser. I'm wondering if DLC was released/planned via this system which is why it gave you the ability to make room on your storage devices. You can delete any content as you would from the main Dreamcast BIOS menu.
Does anybody know any more about these features? Be interesting to see if any of the content added to Dead or Alive Ultimate was planned for DLC, or if there was any additional parts to it. Interesting feature nonetheless.