（方向性）

• Tagを使って、目的のオブジェクトを特定する。
• 「配列」と「foreach」の組み合わせで処理を行う。

（スクリプト）

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class HumanHP : MonoBehaviour
{
    public GameObject effectPrefab;
    public AudioClip sound;
    public int Hp;

    // ★追加
    private GameObject[] targets;
    public GameObject effectPrefab2;

    private void OnCollisionEnter(Collision collision)
    {
        if (collision.gameObject.CompareTag("Toge"))
        {
            Destroy(collision.gameObject);
            GameObject effect = Instantiate(effectPrefab, collision.transform.transform.position, Quaternion.identity);
            Destroy(effect, 1.0f);
            AudioSource.PlayClipAtPoint(sound, Camera.main.transform.position);

            Hp -= 1;
            if (Hp == 0)
            {
                // ★追加
                targets = GameObject.FindGameObjectsWithTag("Hana");

                foreach(GameObject i in targets)
                {
                    Destroy(i);

                    GameObject effect2 = Instantiate(effectPrefab2, i.transform.position, Quaternion.identity);
                    Destroy(effect2, 1.0f);
                }

                Destroy(transform.root.gameObject);
            }
        }
    }
}