Mark Kobayashi was a Japanese man whom Grace's parents had arranged for her to marry back East.
He was born and raised back East in Japan. Mark's parents were traditional Japanese.
Grace's parents also being traditional, arranged for him to date their daughter, and wanted her to marry him. Grace thought she might marry him eventually, but not right away.
To Grace's great annoyance, her mother called her regularly to ask her when she would get a serious job, and when she'd accept a date with the 'nice Japanese boy' mom had selected. He still hadn't been engaged to anyone by the time she traveled to German in 1995. To try to ease things between them, she told her mother to tell him she would be staying in New Orleans for a while longer.
Grace was just still not ready to settle down, and planned to remain working for Gabriel Knight for the time being.
Personality and traits
He was destined for arranged marriage to Grace by her parents. Grace's mom called her regularly asking when she would accept a date to the 'nice Japanese boy" she had selected for her.
Other than that, it's not known how he felt about the arrangement of marriage between his and Grace's family. If the novelization implies anything, he was just as coerced and pushed into the arrangement, as he ends up engaged to someone else.
Behind the scenes
IT appears that in GK2 hintbook information/novelization that Grace hadn't yet accepted a date with Mark, and he hadn't yet been engaged to anyone.
In GK2 itself, Grace is on the phone with her mom, talking about plans. Before she hangs up she says she tells her mom to tell 'him' (which is apparently a reference to "Mark") that she is going to be in New Orleans for longer, and that she's 'not ready for that yet' this is a reference to dating and marrying Mark Kobiyashi (as confirmed in the hintbook).
In the novelization of GK2 his name is mentioned. However, details are changed, and its mentioned he's gotten engaged, and that Grace missed out. Her mother is highly disappointed in her daughter.
All references to Mark Kobayashi are removed in the 20th Anniversary edition for whatever reason. This rather destroys the context of the reference made in GK2, although the context is not easy to make out in the game itself, so is easily missed.
- Grace (GK1): "My folks want me to get married to a boy back east--Mark Kobayashi. His parents are traditional Japanese, too. I might eventually, but right now...."
- GK2 Hintbook, pg 31: "Just to make things more annoying, her mother calls regularly to ask her when she will get a serious job, and when she'll accept a date with the "nice Japanese boy" mom has selected.
- Grace (GK2): "I don't know what you should tell him. Tell him I'm going to be here a while. I'm not ready for that yet.
- GK2 Hintbook, pg 31