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 briliant 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 grandpa and wish that his grampa would have just lived a little longer to be with him.

MegaMan Battle Network 3
Tadashi first appears in MegaMan Battle Network 3 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 and also about personal things. The hologram disappears eventually because Alpha was destroyed.

MegaMan 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. During the final battle with Nebula Grey, Tadashi's voice seems to reach Lan though SoulNet and encourage him to win.

Anime
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.EXE and sealed him.

In Episode 15 of Axess, it is revealed that, in his youth, he created the Net Wrecker, a device which can boost a Net Navi's power to epic porportions. He later exchanged the Wrecker for some ramen.

A hologram of the Beyondard version of Tadashi Hikari appeared in episode 20 of Rockman EXE 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.EXE 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 similars to the name of his original counterpart, which is called Dr. Light and Dr. Right.