Tadashi Hikari

Tadashi Hikari (光正) is the father of Yuichiro Hikari and grandfather of Lan Hikari and Hub Hikari. He was a kind old man and a brilliant scientist, though sadly he never got to live long enough to see the birth of his grandsons, but he would be very proud of them. Lan still loves his grandfather and wished that he would have just lived a little longer to be with him. Hikari was Dr. Light's counterpart in the Mega Man Battle Network universe.

Mega Man Battle Network 3
Tadashi first appears after Alpha is defeated. There is a strange door left over which MegaMan and Lan go into. Inside is the saved memories and persona of Tadashi. He talks to Lan about Alpha's origins and also about personal things such as the family. Lan wants him to escape with them, but he can't because he only exists in Alpha. The hologram disappears eventually because Alpha was destroyed.

Mega Man Battle Network 5
He appears in flashbacks which show him working with Lord Wily on SoulNet with the intention of bringing peace to the world. It is shown that while they did extensive research, they decided to leave it up to their descendants to finish. During the final battle with Nebula Grey, Tadashi's voice seems to reach Lan though SoulNet and encourages him to win. This gives Lan the strength to fight SoulNet and Nebula Grey.

MegaMan NT Warrior
Tadashi Hikari appeared in a flashback in Episode 23 of the first season, where it's revealed he was one of the scientists that worked in the creation of PharaohMan and sealed him.

MegaMan NT Warrior Axess
In Episode 15 of Axess, it is revealed that, in his youth, he created the Net Wrecker, a device which can boost a NetNavi's power to epic proportions. He later exchanged the Wrecker for some ramen. Curiously, the Net Wrecker works with the Advanced PET, invented immediately prior to the events of Axess, years after Dr. Hikari died.

Rockman EXE: Program of Light and Dark
In the Stream movie, an evil program is named after him, and he is seen in a flashback.

Rockman EXE Beast
A hologram of the Beyondard version of Hikari Tadashi appeared in Episode 20 of Beast. He talked about how Beyondard came into existence, how Dr. Wily of Beyondard, now but a conscious stored within an Android Brain, created the Beast Factor, and how Iris was created. He also created the Synchronizer, Trill, in order to win the war against the Zoanoroids.

Etymology

 * Hikari (光) means Light and Tadashi (正) can mean Right, both similar to the name of his original counterpart, who is referred to as Dr. Light and Dr. Right.