Blue Promise
Trying to fight the Heterodyne that appeared in Hokkaido has proven to be nothing but trouble, and now it looks like the team is in for more of the same. Not only is the Self Defence Force unable to join in the battle until the appropriate legislation has passed, but Akagi's new friend Ishihara has stolen his Dai-Guard access card! Still the team cannot stand idly by, and it falls to Aoyama to convince Arisa, an old friend from university, to help them find a way to lure the Heterodyne to Dai-Guard. But that can only happen if he can make Arisa see past the anger she feels for Aoyama's abrupt departure from Hokkaido three years ago…
Aired 15/02/2000EP 20 - Blue Promise
Dai-Guard
Thirteen years after their sudden disappearance, an alien race known as the Heterodyne resurface without warning. To combat the Heterodyne, three office workers from the 21st Century Security Corporation operate Dai-Guard - a giant robot no longer regarded as an oversized paperweight. Unfortunately, Dai-Guard is somewhat obsolete and in disrepair. It's a tough job, but salarymen can also save the world.
(Source: Anime News Network)